feat: refactor to use gcc types

kernel/libc/libc.c

@@ -8,7 +8,7 @@
 #include <types.h>
 #include "libc.h"
 
-int memcpy(u8 *dst, const u8 *src, int amount) {
+int memcpy(uint8_t *dst, const uint8_t *src, int amount) {
     for (int i = 0; i < amount; i++) {
         dst[i] = src[i];
     }