pointer, it's inconsistent that it only sets this GV's GvGP to 0 if
this GV happened to have the last reference. Why should this GV care if
it had the last reference? So always set it to 0. It's free. Gone.
p4raw-id: //depot/perl@27320
if (--gp->gp_refcnt > 0) {
if (gp->gp_egv == gv)
gp->gp_egv = 0;
+ GvGP(gv) = 0;
return;
}