Tests: Set policies in 'complex' tests

These tests cover the OLD behavior of some policies.  Set them to
OLD to avoid warnings in the test output.  Leave a comment that
explains why this is done here but not recommended in general.
cmake: Avoid overwriting compiler name if specified repeatedly.

If CMake is invoked repeatedly on the command line with the
compiler of a language specified by name, don't replace the
cached value with the un-resolved name if the resolved name is
the same as the path in the cache.
Merge topic 'fix-broken-re-cmake' into next

a12e4e78 cmake: Avoid overwriting compiler name if specified repeatedly.
Revert "genex: Allow genex caching of config genex on single-config generators"

This reverts commit 93d441b5341b3288f113d7e9c3a488bb23497547.
Merge topic 'revert-stray-topic' into next

db347362 Revert "genex: Allow genex caching of config genex on single-config generators"
Merge topic 'fix-complex-test-policies' into next

fb95f820 Tests: Set policies in 'complex' tests