[ASan] Fix interface_symbols_darwin.c test

by manually adding __asan_mz_* to the generated interface functions list.

Declaring these functions in asan_interface_internal.h doesn't work quite well:
their prototypes must match the prototypes of zone functions in malloc/malloc.h,
but some of the types (e.g. malloc_zone_t and size_t) aren't available in
asan_interface_internal.h

llvm-svn: 228290