LibC: Add memory.h that just includes string.h

There are a lot of ports trying to include memory.h. This is not posix
but glibc just includes string.h. I think this is just to privide mem*
functionss...?

userspace/libraries/LibC/include/memory.h

@@ -0,0 +1,6 @@
+#ifndef _MEMORY_H
+#define _MEMORY_H 1
+
+#include <string.h>
+
+#endif