Fix TooManyThreads valgrind error

This test requires that CHPL_RT_NUM_THREADS_PER_LOCALE is unset for correct
output, but our valgrind testing sets this variable in order to run.  Therefore,
the test is not useful under these circumstances.  The effort to make the
prediff more correctly react to this variable being set seemed much greater than
the payoff, so I left a note in the test of how it could be done and turned it
off for valgrind.
Adjusted the prediff to squash .bad mismatch.
Merge pull request #718 from vasslitvinov/fix-hplx.chpl-prediff

Adjusted the prediff to squash .bad mismatch for hplx.chpl.

For this test:

  test/distributions/dm/hplx.future

the erroneous output can be quite diverse.
I set the prediff - specifically, a case in PREDIFF -
to filter out everything except the correct output
and errors, aiming at a clean match against .bad.

When I did that, I saw "error: attempt to dereference nil"
reported only in ReplicatedDist.chpl, so I filtered
out that error line. Last night we saw that error
reported in ChapelBase.chpl instead. So this change
is to relax the filter to allow that error in any file.
Merge pull request #717 from lydia-duncan/tooManyThreadsForValgrind

Fix TooManyThreads valgrind error

This test requires that CHPL_RT_NUM_THREADS_PER_LOCALE is unset for correct
output, but our valgrind testing sets this variable in order to run. Therefore,
the test is not useful under these circumstances. The effort to make the
prediff more correctly react to this variable being set seemed much greater than
the payoff, so I left a note in the test of how it could be done and turned it
off for valgrind.