pythongh-59703: restore include of mach-o/dyld.h (pythongh-112309)

On older versions of macOS, _NSGetExecutablePath appears to only
be available via macho-o/dyld so macho-o/dyld.h is still needed.

Author: ned-deily

Modules/getpath.c

@@ -18,6 +18,7 @@
 
 #ifdef __APPLE__
 #  include <dlfcn.h>
+#  include <mach-o/dyld.h>
 #endif
 
 /* Reference the precompiled getpath.py */