Max logical performance

Add a performance suite to keep track of the tests we know were
hurt by turning off hyperthreading.  The suite consists of symlinks
of the relevant files in a separate directory, so as not to clutter the
release or other, more interesting tests.  Since these tests are
already going to be run in other modes, skip testing them except
for performance runs.  Their performance runs set the value of
CHPL_RT_NUM_THREADS_PER_LOCALE to MAX_LOGICAL.

Tests tracked in this way include
- The release version of HPL
- NAS Parallel Benchmarks EP (FT and IS were skipped because we
   don't run their affected sizes)
- EP STREAM fragmented
- The release version of the Shootout fannkuch redux
- The release version of the Shootout spectral-norm
- The fastest version of the Shootout mandelbrot