test-lib-main.sh: check --run before prereqs
When skipping tests using --run there's no reason to complain about
missing prereqs for a test that's being skipped anyway.
Move the $run_list check ahead of the $test_prereq check where it
belongs to avoid bogus missing prerequisite messages when skipping
the tests that set them.
With this ordering, the "--run" default "partially active" --quiet
mode avoids generating spammy messages about missing prereqs that
resulted from skipping tests (via "--run") that would have set them.
Signed-off-by: Kyle J. McKay <mackyle@gmail.com>