Merge topic 'makefile-normalize-depfile'

30926620bb Merge branch 'backport-3.21-makefile-normalize-depfile'
6bc6ffb9a9 Merge branch 'backport-3.20-makefile-normalize-depfile'
6a6efdcaed Makefiles: Normalize compiler-generated depfile paths

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !6297