Use string.h instead of strings.h . Fixing hpux 10.20 bustage

gfx/src/xprint/nsXPrintContext.cpp

@@ -25,7 +25,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <errno.h>
-#include <strings.h>
+#include <string.h> /* for strerror & memset& memset  */
 #include "xlibrgb.h"
 #include "nsXPrintContext.h"
 #include "nsDeviceContextXP.h"