Only free Render filter names on last screen close

Hotplugging screens causes the render filter names to get freed while
still in use; wait for the last core screen to be closed before
freeing them. That only happens at server reset, when we want them to
be freed.

Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>

render/filter.c

@@ -273,7 +273,10 @@ PictureResetFilters(ScreenPtr pScreen)
 
     free(ps->filters);
     free(ps->filterAliases);
-    PictureFreeFilterIds();
+
+    /* Free the filters when the last screen is closed */
+    if (pScreen->myNum == 0)
+        PictureFreeFilterIds();
 }
 
 int