Include string.h.

gas/config/ho-sysv.h

@@ -17,6 +17,7 @@
    along with GAS; see the file COPYING.  If not, write to
    the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
 
+#include <string.h>
 extern int free ();
 extern char *malloc ();