Merge topic 'CheckCompilerFlags-revert-linker-warnings'

4941887d7d CheckCompilerFlags: Revert "Catch linker warning about ignored flags"
c2341ece47 CheckLinkerFlag: Catch linker warning when the checked flag is ignored

Acked-by: Kitware Robot <kwrobot@kitware.com>
Tested-by: buildbot <buildbot@kitware.com>
Merge-request: !7190