Merge topic 'ninja-scandep-preprocessor-output'

312ced65 cmNinjaTargetGenerator: Fix scan rule PREPROCESSED_SOURCE placeholder
1dd9c4ab cmNinjaTargetGenerator: Clarify GetScanBuildStatement condition
d94b2388 cmNinjaTargetGenerator: Simplify scan rule response file selection

Acked-by: Kitware Robot <kwrobot@kitware.com>
Tested-by: Ben Boeckel <ben.boeckel@kitware.com>
Merge-request: !6227