add memcpy(), memmove(), memset()

src/mem.h

@@ -1,6 +1,21 @@
 #ifndef MEM_H
 #define MEM_H
 
+static inline void * memcpy(void * dest, const void * src, size_t n)
+{
+    return __builtin_memcpy(dest, src, n);
+}
+
+static inline void * memmove(void * dest, const void * src, size_t count)
+{
+    return __builtin_memmove(dest, src, count);
+}
+
+static inline void * memset(void * dest, int val, size_t count)
+{
+    return __builtin_memset(dest, val, count);
+}
+
 static inline void memset32(void * dest, uint32_t val, size_t count)
 {
     uint32_t r0, r1;