Push the auto-SRCS determination logic down into bsd.test.mk

Signed-off-by: Garrett Cooper <yanegomi@gmail.com>
Add logic for integrating in prove tests

This is a simple cutover/for other tests that won't be
easy to integrate into ATF, like pjdfstest.

Signed-off-by: Garrett Cooper <yanegomi@gmail.com>
Integrate pjdfstest into the build

Signed-off-by: Garrett Cooper <yanegomi@gmail.com>
Fix a compile-time warning with WARNS?=6

Signed-off-by: Garrett Cooper <yanegomi@gmail.com>