ValueMapper: Resolve cycles on the new nodes

Fix a major bug from r265456.  Although it's now much rarer, ValueMapper
sometimes has to duplicate cycles.  The
might-transitively-reference-a-temporary counts don't decrement on their
own when there are cycles, and you need to call MDNode::resolveCycles to
fix it.

r265456 was checking the input nodes to see if they were unresolved.
This is useless; they should never be unresolved.  Instead we should
check the output nodes and resolve cycles on them.

llvm-svn: 266258