Merge topic 'config-case'

ff02a592bc cmLocalGenerator: Avoid using upper-case config when not necessary
a4b76c237d cmLocalGenerator: Clarify local variable name in GetTargetFlags
25a920e827 cmLocalGenerator: Convert GetStaticLibraryFlags to take original-case config

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !4558