nag-20150528 regression with 6.2 build 6212

[nncarlson]

The old test case nag/nag-20150528.f90 started failing again with 6.2 build 6212, but in what appears to be an entirely different way. The test case is relatively long and complex (2 files), and can likely be reduced substantially for the current issue, and then needs to be reported.

The error occurs when using -C and no optimization flag or -O0, but goes away with -O1 or higher.