virfile: Resolve Coverity RESOURCE_LEAK

With the virGetGroupList() change in place - Coverity further complains
that if we fail to virFork(), the groups will be leaked - which aha seems
to be the case. Adjust the logic to save off the -errno, free the groups,
and then return the value we saved
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>

src/util/virfile.c

@@ -2000,8 +2000,11 @@ virFileOpenForked(const char *path, int openflags, mode_t mode,
     }
 
     pid = virFork();
-    if (pid < 0)
-        return -errno;
+    if (pid < 0) {
+        ret = -errno;
+        VIR_FREE(groups);
+        return ret;
+    }
 
     if (pid == 0) {