Guarantee a call to memset, even when optimizing

memclear.c

#include <stddef.h>

static inline void *memclear(void *dest, size_t len){
	asm inline volatile("call memset"
	                   :
	                   :"r"(dest),
	                    "r"(0),
	                    "r"(len)
	                   :
	);
	return dest;
}