tests: move coverage about BUILT_SOURCES Basically a backport of some tests from Automake-NG. * t/built-sources-check.sh: Sync it with the version in the ng/master branch. Accordingly, move part of the checks out ... * t/built-sources-install.sh: ... into this new test, synced from ng/master as well. * t/built-sources-subdir.sh: Minor tweaks and enhancements to sync it with the version in ng/master. * t/built-sources-cond.sh: New test, synced from ng/master. * t/built-sources.sh: Likewise, with minor edits to avoid a spurious failure. * t/built-sources-fork-bomb.sh: Likewise. * t/list-of-tests.mk: Update. Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>