__glXDRIscreenProbe: free screen when DRI2Connect fails, instead of leaking it

Reported with other leaks found by cppcheck in bugzilla #50281
https://bugs.freedesktop.org/show_bug.cgi?id=50281

V2: goto existing error handler, instead of replicating more of it here

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Reviewed-by: Keith Packard <keithp@keithp.com>

glx/glxdri2.c

@@ -946,7 +946,7 @@ __glXDRIscreenProbe(ScreenPtr pScreen)
                      &screen->fd, &driverName, &deviceName)) {
         LogMessage(X_INFO,
                    "AIGLX: Screen %d is not DRI2 capable\n", pScreen->myNum);
-        return NULL;
+        goto handle_error;
     }
 
     screen->base.destroy = __glXDRIscreenDestroy;