If mimalloc is built with MI_OSX_INTERPOSE=OFF MI_OSX_ZONE=OFF, realpath test case in test-api is broken

The failure confirmed on macOS Ventura (x86_64) and Snow Leopard (ppc).
See: https://github.com/macports/macports-ports/pull/19357?notification_referrer_id=NT_kwDOBXwLlrM2OTk0NjU1NzU2OjkyMDE1NTEw#issuecomment-1627030209

It seems to fail here:
```
Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_INVALID_ADDRESS at address: 0x96d19b68
0x00023b3c in _mi_free_generic ()
(gdb) where
#0 0x00023b3c in _mi_free_generic ()
#1 0x0002c720 in mi_heap_realpath () at _string.h:80
#2 0x00004ed4 in main ()
```

Reproduce the realpath case in test-api with MI_OSX_INTERPOSE=OFF and MI_OSX_ZONE=OFF on macOS, then inspect the mi_heap_realpath failure at _string.h:80 and the _mi_free_generic backtrace. Done means the test no longer crashes under these configurations and the existing test-api behavior passes on the affected platforms.

Written by the indexing model from the issue text.