Remove the definition of _Unwind_Resume on OSX.

This is unnecessary for me when using Makefile.simple, as far as I can tell.
And it's actively harmful when using "mymake", because then we get this
non-inline variable defined in every .o file, which leads to
multiple-definition errors at link time.

Maybe it's no longer needed?

hyper.h

@@ -507,12 +507,6 @@ void IMAGESAVE(SDL_Surface *s, const char *fname);
 
 #endif
 
-// for some reason I need this to compile under OSX
-
-#if ISMAC
-extern "C" { void *_Unwind_Resume = 0; }
-#endif
-
 template<class T> struct dynamicval {
   T& where;
   T backup;