autotools/: Allow check target to be invoked w/o the need to issue a build.

We need to have the test list generated before running the check target.
Migrated igt_command_line.sh to tests/ from lib/tests/, which allows to
building the tests and execute the script.

This would allow cleaning followed by a make check.

Also assembler/ directory needs also to be adjusted in order for this
to work.

Kept the possibility to invoke tests/igt_command_line.sh to determine
which test is failing.

Signed-off-by: Marius Vlad <marius.c.vlad@intel.com>
Url: https://patchwork.freedesktop.org/series/6539/
Reviewed-By: Chris Wilson <chris@chris-wilson.co.uk>
8 files changed