util: Move locale.h include from virutil to virstring

Commit 5c54d29aae forgot to do that when moving the only function
using it and it broke the build on some platforms.

Signed-off-by: Martin Kletzander <mkletzan@redhat.com>

src/util/virstring.c

@@ -24,6 +24,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <regex.h>
+#include <locale.h>
 
 #include "base64.h"
 #include "c-ctype.h"

src/util/virutil.c

@@ -45,7 +45,6 @@
 #include <sys/ioctl.h>
 #include <string.h>
 #include <termios.h>
-#include <locale.h>
 
 #if WITH_DEVMAPPER
 # include <libdevmapper.h>