virnetdevbandwidth: Include virutil.h

One of the latest patches (9a8fc3ef) introduced call of
geteuid(). However, not all systems have the function
implemented, e.g. mingw. Therefore, we fail to build on those
system. The fix consist of including virutil.h which defines
geteuid in needed. Sigh.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

src/util/virnetdevbandwidth.c

@@ -28,6 +28,7 @@
 #include "viralloc.h"
 #include "virerror.h"
 #include "virstring.h"
+#include "virutil.h"
 
 #define VIR_FROM_THIS VIR_FROM_NONE