virnetsocket: Mark @spawnDaemonPath of virNetSocketNewConnectUNIX() unused

The virNetSocketNewConnectUNIX() function was changed in
48f66cfe3e. And its WIN32 version (which just reports an error)
was updated too, but this new argument @spawnDaemonPath was not
marked as unused.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>

src/rpc/virnetsocket.c

@@ -774,7 +774,7 @@ int virNetSocketNewConnectUNIX(const char *path,
 }
 #else
 int virNetSocketNewConnectUNIX(const char *path G_GNUC_UNUSED,
-                               const char *spawnDaemonPath,
+                               const char *spawnDaemonPath G_GNUC_UNUSED,
                                virNetSocket **retsock G_GNUC_UNUSED)
 {
     virReportSystemError(ENOSYS, "%s",