added __attribute__((optnone))

So, setjmp/longjmp and non-volatile local variables doesn't really mix.
This patch adds __attribute__((optnone)) to describe blocks, to prevent
compilers from optimizing tests and messing up local variables. This
shouldn't be a permanent fix, but does mean tests compiled with
optimizations won't break.

snow/snow.h

@@ -1122,6 +1122,7 @@ static int snow_main_function(int argc, char **argv) {
 		struct _snow_desc_func df = { #name, &snow_test_##name }; \
 		_snow_arr_push(&_snow.desc_funcs, &df); \
 	} \
+	__attribute__((optnone)) \
 	static void snow_test_##name()
 
 #define subdesc(name) \