[NewGVN] Change test to reflect difference between GVN and NewGVN.

The current GVN algorithm folds unconditional branches to, it claims,
expose more PRE oportunities. The folding, if really needed,
(which is not sure, as it's not really proved it improves analysis)
can be done by an earlier cleanup pass instead of GVN itself.
Ack'ed/SGTM'd by Daniel Berlin.

Differential Revision:  https://reviews.llvm.org/D28117

llvm-svn: 290546