From Abdulaziz Ghuloum. Adds special case for Snow Leopard.

configure.ac

@@ -273,6 +273,14 @@ if test x$TARGET = xX86 || test x$TARGET = xX86_WIN32 || test x$TARGET = xX86_64
     fi
 fi
 
+case "$target" in
+    i?86-apple-darwin10*)
+	AC_DEFINE(FFI_MMAP_EXEC_WRIT, 1,
+		  [Cannot use malloc on this target, so, we revert to
+		   alternative means])
+    ;;
+esac 
+
 AC_CACHE_CHECK([whether .eh_frame section should be read-only],
     libffi_cv_ro_eh_frame, [
 	libffi_cv_ro_eh_frame=no