Add test for depmod using search dirs with same prefix

Test depmod with search dirs "foo" and "foobar". Previously to 49b33c1
("depmod: do not allow partial matches with "search" directive") we were
failing this test due to matching the prefix without checking if
it's the full dir name.

We are adding 2 tests here in order to catch the case we only pass the
test due to processing the directories in a favourable order.
9 files changed