Merge topic 'clang-imsvc'

faed1562fb Merge branch 'backport-3.23-clang-imsvc' into clang-imsvc
23a52561c7 Clang: Use -imsvc flag without space to support Clang tools

Acked-by: Kitware Robot <kwrobot@kitware.com>
Reviewed-by: Raul Tambre <raul@tambre.ee>
Acked-by: hihig2001 <hihig@bluehole.net>
Merge-request: !7274