use _setjmp/_longjmp on OS X

include/mruby/throw.h

@@ -20,11 +20,19 @@ typedef mrb_int mrb_jmpbuf_impl;
 
 #include <setjmp.h>
 
-#define MRB_TRY(buf) do { if (setjmp((buf)->impl) == 0) {
+#if defined(__APPLE__)
+#define MRB_SETJMP _setjmp
+#define MRB_LONGJMP _longjmp
+#else
+#define MRB_SETJMP setjmp
+#define MRB_LONGJMP longjmp
+#endif
+
+#define MRB_TRY(buf) do { if (MRB_SETJMP((buf)->impl) == 0) {
 #define MRB_CATCH(buf) } else {
 #define MRB_END_EXC(buf) } } while(0)
 
-#define MRB_THROW(buf) longjmp((buf)->impl, 1);
+#define MRB_THROW(buf) MRB_LONGJMP((buf)->impl, 1);
 #define mrb_jmpbuf_impl jmp_buf
 
 #endif