Remove array_{repr,str}_builtin functions from strfuncs.c #17138

Those two functions depend on the dump_data function, which looks buggy to me, and they are never used in practice as they are overloaded when arrayprint is loaded. And arrayprint itself is loaded when numeric is loaded, which takes place when numpy is loaded. That all looks fishy as heck. I propose that the default ndarray str and repr functions be set to the arrayprint implementations.

The dump_data function could probably be fixed but I don't think it is worth the effort. The current setup dates back to the time when numpy enhancements came in separate modules and all the strings were ascii.