scripts: Include plugin arguments when run with -analyze

This allows:
    tartan -cc1 -analyze …
as a pass-through for:
    clang -cc1 -analyze … -add-plugin tartan …
tests: Add a non-GLib test

As a follow up to commit 915a744037d93abfcaab8b35e98e281cf88bb132, add a
non-GLib test, which checks that scanning a file which doesn’t include
glib.h succeeds.