meson: if dep_dl is an empty list, it's not a dependency object

It's ok to use an empty list for dependencies:, but it's not ok to try to
use the found() method of it.

See also https://github.com/mesonbuild/meson/issues/2324

Signed-off-by: Jon Turney <jon.turney@dronecode.org.uk>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>
1 file changed