Tests: Fix RunCMake infrastructure for LCC and CMP0129
Since !6643 (merged) we intended to enable policy
CMP0129
in RunCMake tests via -DCMAKE_POLICY_DEFAULT_CMP0129=NEW
.
Fix the condition activating that to check CMAKE_C_COMPILER_ID
where
it is always available.
Remove now-unnecessary CMP0129 settings in RunCMake cases.
Edited by Brad King