Merge topic 'preserve-compiler-arg1'

211a9deac1 Preserve CMAKE_${lang}_COMPILER_ARG1 from existing CMakeCache.txt
b4de4217ae Tests: Simplify RunCMake.CompilerArgs no-clean cases

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: buildbot <buildbot@kitware.com>
Merge-request: !7122