build: Add "dist" and "distcheck" targets
* CMakeLists.txt: Include G10AddDistTargets. Set EXTRA_DIST. Add "dist" and "distcheck" target. * cmake/modules/G10AddDistTarget.cmake, cmake/modules/g10_dist.sh.in, cmake/modules/g10_distcheck.sh.in: New.
This adds "dist" and "distcheck" build targets which are similar to the
corresponding automake targets. The tarball is created with git-archive
so that that the targets can only be used in a cloned repo.
- GnuPG-bug-id: T7262