feat(libc): add freestanding types and string helpers

include/string.h

@@ -0,0 +1,14 @@
+#ifndef FROSTBYTE_STRING_H
+#define FROSTBYTE_STRING_H
+
+#include "types.h"
+
+void* memset(void* dest, int value, usize count);
+void* memcpy(void* dest, const void* src, usize count);
+void* memmove(void* dest, const void* src, usize count);
+int memcmp(const void* a, const void* b, usize count);
+usize strlen(const char* str);
+int strcmp(const char* a, const char* b);
+int strncmp(const char* a, const char* b, usize count);
+
+#endif