depend-cleanup.sh: Handle kqtest being renamed to kqueue_test.

bmake will not think that object files such as read.o are out of date
due to common.h changing since the dependency is only recorded in
.depend.kqtest.read.o in an old object directory.

Reviewed by: markj
Fixes: 68fe988a40ca kqueue tests: Simplify the test runner
Sponsored by: DARPA
Differential Revision: https://reviews.freebsd.org/D35820