Test: scheduler: Build special libpe_*_test libraries.

We now need a special version of the scheduler libraries in order to use
the mocked up functions provided by libcrmcommon_test in the scheduler
tests. Also, make sure the existing scheduler unit tests link against
the appropriate test library versions.

See b6966c52c8c2b7c493bb4d7136a6911ebb2b0d1f for more details.