qa/756: rebuild binary if running QA from a git tree
qa/756: rebuild binary if running QA from a git tree

The perfevent/perfevent_test binary has a dependency on files
in src/pmdas/perfevent ... for testsuite runs this was all OK,
but out of the git tree there was possible bit rot ... easiest
fix is to force a rebuild.

adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp