Fix OMPT state maintenance for barriers and missing init of implicit task id.

Fix OMPT support for barriers so that state changes occur even if OMPT_TRACE turned off. 
These state changes are needed by performance tools that use callbacks for either 
ompt_event_wait_barrier_begin or ompt_event_wait_barrier_end.  Change ifdef flag to OMPT_BLAME 
for callbacks ompt_event_wait_barrier_begin or ompt_event_wait_barrier_end rather than 
OMPT_TRACE -- they were misclassified.  Without this patch, when the runtime is compiled with 
LIBOMP_OMPT_SUPPORT=true, LIBOMP_OMPT_BLAME=true, and LIBOMP_OMPT_TRACE=false, and a callback 
is registered for either ompt_event_wait_barrier_begin or ompt_event_wait_barrier_end, then an 
assertion will trip.  Fix the scoping of one OMPT_TRACE ifdef, which should not have surrounded 
an update of an OMPT state.  Add a missing initialization of an OMPT task id for an implicit task.

Patch by John Mellor-Crummey

Differential Revision: http://reviews.llvm.org/D10759

llvm-svn: 240970