Add HAVE_STRINGS_H for better POSIX compliance.

cpukit/libmisc/shell/main_rm.c

@@ -65,6 +65,9 @@ __FBSDID("$FreeBSD: src/bin/rm/rm.c,v 1.58 2006/10/31 02:22:36 delphij Exp $");
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#ifdef HAVE_STRINGS_H
+#include <strings.h>
+#endif
 #include <unistd.h>
 
 /* RTEMS specific changes */