Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Repo-copy tools/regression/usr.bin/make to tools/build/make_check
and adjust the path in the Makefile for the upgrade_checks target.
These checks are really feature upgrade checks that should be fast
and just find out whether we need to build a new make before
proceeding with other targets like buildworld. This makes the
place free for a real regression test suite in the old place.

Make the tests runnable on a read-only src. To do this you must make sure
that you create one of the object directories make knows (see make(1)).
This uses the -C flag, so add a test that checks that make actually accepts
-C. Also fix the test that selects csh via the .SHELL target to work for
tcsh users too.

This commit renames shell_test to shell_test.sh. There is no history
to preserve so go without a repo-copy.

Reviewed by: ru