[8u] RFR: 8237951: CTW: C2 compilation fails with "malformed control flow"

[Roland Westrelin]

The patch from the fix applies cleanly but it relies on
Node::find_out_with() that's missing from 8. The backport below cherry
picks that method from 8066312 (Add new Node* Node::find_out(int opc)
method).

http://cr.openjdk.java.net/~roland/8237951.8u/webrev.00/

Initial change:
https://bugs.openjdk.java.net/browse/JDK-8237951
https://hg.openjdk.java.net/jdk/jdk/rev/c7152f7e01a6

Tested with tier1.

Roland.