Issue #18203: Replace malloc() with PyMem_RawMalloc() at Python initialization * Replace malloc() with PyMem_RawMalloc() * Replace PyMem_Malloc() with PyMem_RawMalloc() where the GIL is not held. * _Py_char2wchar() now returns a buffer allocated by PyMem_RawMalloc(), instead of PyMem_Malloc()