added target_always_include #26

Job	Run time
build (ubuntu-latest, Debug, gcc)	1m 3s
build (ubuntu-latest, Debug, clang)	55s
build (windows-latest, Debug, cl)	2m 33s
build (windows-latest, Release, cl)	2m 14s
build (ubuntu-latest, Release, clang)	53s
build (ubuntu-latest, Release, gcc)	58s
	8m 36s

Provide feedback