[native] Replace the bundled properties map with a linked list - #12551

…2552)

Part of #12533 (drop the `libc++` dependency), stacked on #12551.

`AndroidSystem` kept five of its members in `std::string` / `std::array<std::string, 1>`: `primary_override_dir`, `native_libraries_dir`, `app_code_cache_dir`, `single_app_lib_directory` and `override_dirs`.

Because they are `inline static` with dynamic initialization, the compiler emits a guard variable **and** an `atexit` registration for them in *every* translation unit that includes `android-system.hh` — even in ones that never touch them. `logger.cc`, `internal-pinvokes-clr.cc`, `internal-pinvokes-shared.cc` and `android-system-shared.cc` each paid four libc++ references (`~basic_string`, `operator delete`, `__cxa_guard_acquire`, `__cxa_guard_release`) without using a single one of these directories:

```
$ llvm-nm --undefined-only logger.cc.o | llvm-cxxfilt
std::__ndk1::basic_string<...>::~basic_string()
operator delete(void*)
__cxa_guard_acquire
__cxa_guard_release

$ llvm-objdump -r logger.cc.o | grep _ZGV | llvm-cxxfilt
guard variable for xamarin::android::AndroidSystem::override_dirs
guard variable for xamarin::android::AndroidSystem::app_code_cache_dir
guard variable for xamarin::android::AndroidSystem::native_libraries_dir
guard variable for xamarin::android::AndroidSystem::primary_override_dir
guard variable for xamarin::android::AndroidSystem::single_app_lib_directory
```

## What changed

All five become plain pointers. The three path members are `const char*` initialized to `""` and assigned once, early during startup, with a copy made by a new `Util::duplicate_string()` helper that aborts if the allocation fails. Pointers to a string literal are **constant-initialized**, so neither a guard variable nor an `atexit` registration is emitted.

The two directory arrays become plain `const char*` arrays whose entries are `malloc`ed, which also drops an `operator new[]` from the non-split-APK path.

Since there is no longer a fixed-size buffer anywhere, there is also no hard limit on the path length and no abort when it is exceeded — which is what NativeAOT's `char[SENSIBLE_PATH_MAX]` `primary_override_dir` used to do. That lets `primary_override_dir` be shared by all three hosts, removing three `#if defined (XA_HOST_NATIVEAOT)` blocks and `determine_primary_override_dir()` entirely.

## Results

Undefined libc++ references in the three CoreCLR archives — **58 → 31**:

| object | before | after |
|---|---:|---:|
| `assembly-store.cc.o` | 13 | 11 |
| `host.cc.o` | 11 | 11 |
| `android-system.cc.o` | 11 | 5 |
| `timing-internal.cc.o` | 5 | 2 |
| `logger.cc.o` | 4 | **0** |
| `internal-pinvokes-shared.cc.o` | 4 | **0** |
| `internal-pinvokes-clr.cc.o` | 4 | **0** |
| `android-system-shared.cc.o` | 4 | **0** |
| `typemap.cc.o` | 2 | 2 |

Every `__cxa_guard_*` reference coming from this header is gone; the only ones left are `host.cc`'s own function-local statics.

`libnet-android.release.so`: **539,464 → 536,368 bytes (−3,096)**.

The DEBUG-only code paths were compile-checked separately (there is no Debug ninja directory) and go from 12 to 7 references; `llvm-nm` confirms `add_system_property`, `find_bundled_property` and `setup_environment_from_override_file` are genuinely emitted rather than silently `#if`'d out.

CoreCLR, NativeAOT and MonoVM all build clean.

…12571)

Part of #12533: remove the remaining allocating C++ library types from the CoreCLR assembly store and its decompressed-assembly cache.

<!-- stack-prerequisites -->
All prerequisites (#12541, #12545, #12551, #12552, #12560, #12568, and #12570) have merged. This branch was rebuilt on `main` at `4b0cc8efa9`. The runtime changes are confined to `src/native/clr/host/assembly-store.cc`, with cache regression coverage and APK size baseline updates alongside them. The already-merged startup, timing, DSO-loader, and other prerequisite changes are no longer included in this PR's diff. Upstream's pthread-backed `lock_guard` is preserved.
<!-- /stack-prerequisites -->

### Changes

- Replace `std::deque<WriteRequest>` with an intrusive FIFO linked through `WriteRequest::next`.
- Replace the queued request's `std::unique_ptr<uint8_t[]>` with an explicit `uint8_t *payload`. Allocate the request and payload separately with two `malloc` calls and release both with two `free` calls on every completed or discarded write. If payload allocation fails, release the request and skip the write. No trailing-storage pointer arithmetic or explicit over-alignment is needed.
- Replace the cache directory and per-request `std::string` paths with a process-lifetime directory string and checked `snprintf` formatting. Requests store the descriptor index instead of a path; the writer reconstructs the destination from the immutable cache directory. Replace temporary-file name construction and matching with `snprintf` and `strstr`.
- Use a scoped `CachePath` buffer for directory creation, reads, writes, and stale-file cleanup. Short paths remain on the stack; longer paths retry in an exactly sized `malloc` allocation that is freed on every exit. Formatting and allocation failures are logged and remain non-fatal for the optional cache, unlike the abort-on-failure `Util::format_with_retry` helper.
- Allocate the decompression tracking array and assembly-name table with `calloc`, replacing their `unique_ptr`/`new[]` allocations.
- Extend the existing device cache regression test with a Java Application that supplies a code-cache directory longer than 1 KB. Cover persistence, mapping, corruption recovery, and stale temporary-file cleanup for both ordinary and long paths.

The asynchronous writer, queue byte limit, cache footer validation, and scope-based pthread locking are retained. `Util::LocalPathBufferSize` is the stack fast-path size, not a hard path limit; truncated paths are never used for I/O. The change does not alter linker flags or other runtime hosts.

### Original measurements

These results were recorded on the original pre-rebuild branch, **not on the current revision**:

| Release, arm64 | Before | After |
|---|---:|---:|
| Undefined libc++ references in `assembly-store.cc.o` | 12 | 0 |
| Undefined libc++ references across the CoreCLR host | 12 | 0 |
| `libnet-android.release.so` size | 520,112 bytes | 203,776 bytes |

Reaching zero references allowed the linker to stop pulling members from `libc++_static.a`. Relinking without libc++ also succeeded on that original branch; dropping the linker flag remains a follow-up.

### Current validation status

The malloc fallback passed sanitizer-backed host cases covering stack/heap boundaries, nested lifetimes, allocation failure, and formatting/retry failures. The cache namespace extracted unchanged from the current source, using the real CRC32 and mutex helpers with runtime configuration/property stubs, compiled with the Android NDK for arm64, arm32, and x86_64. A standalone arm64 emulator harness passed cache initialization, asynchronous persistence, mmap reads, corruption recovery, and stale-file cleanup with both short and greater-than-1-KB paths. The generated Java regression-test application also compiled against the Android API. `git diff --check` passes.

A local `dotnet build src/native/native-clr.csproj` restored packages but could not reach native compilation because this worktree lacks `xa-prep-tasks.dll` and `Xamarin.Android.Tools.BootstrapTasks.dll`. The complete native host build and repository device regression suite have **not** been run for this revision; the locally built SDK is unavailable. Binary measurements have not been repeated. The original branch's reported full native builds and binary measurements remain historical, not validation of this revision.