Xquartz: pbproxy: Some debugging about unhandled mime types... this will spam up quick, but will be useful for a while...

(cherry picked from commit 3647215310)

hw/xquartz/pbproxy/x-selection.m

@@ -250,6 +250,11 @@ get_property(Window win, Atom property, struct propdata *pdata, Bool delete, Ato
 	{
 	    string = True;
 	}
+    else
+    {
+        const char *type = XGetAtomName(x_dpy, a);
+        DB("Unhandled X11 mime type: %s", type);
+        Xfree(type);
     }
 
     /*We prefer PNG over strings, and UTF8 over a Latin-1 string.*/