Revert "make clipboard patch obsolete"

This reverts commit 77c51c5a6b.

Having multiple clipboards are useful, for example for plumber scripts.
I've discussed this on IRC and it is useful to have.

x.c

@@ -507,7 +507,6 @@ xsetsel(char *str, Time t)
 	XSetSelectionOwner(xw.dpy, XA_PRIMARY, xw.win, t);
 	if (XGetSelectionOwner(xw.dpy, XA_PRIMARY) != xw.win)
 		selclear_(NULL);
-	xclipcopy();
 }
 
 void