Reorganise allocators

tests/allocator/test_allocator.c

@@ -1,7 +1,7 @@
 #include "test_allocator.h"
-#include "libc/mem_libc.h"
+#include "libc/mem_libc_allocator.h"
 #include "mem_allocator.h"
-#include "mem_arena.h"
+#include "mem_arena_allocator.h"
 #include "tester.h"
 #include <stdbool.h>
 #include <stdlib.h>