Add string.h which includes memset

src/arch/x86_64/c/tasks.c

@@ -12,7 +12,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
-// #include <string.h>
+#include <string.h>
 #include <errno.h>
 #include <tasks.h>
 #include <processor.h>

src/c_kernel/include/string.h

@@ -0,0 +1,19 @@
+// Copyright (c) 2016-2017 Utero OS Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+//
+// Functions are taken from musl/include/string.h
+
+#ifndef STRING_H
+#define STRING_H
+
+#include "bits/alltypes.h"
+
+void* memset(void*, int, size_t);
+
+#endif /* end of include guard: STRING_H */