Fix for OMP_PROC_BIND=spread strategy

The OMP_PROC_BIND=spread strategy fails to assign the master thread the
correct place partition after the first parallel region. Other threads in the
hot team will remember their place_partition, but the master's place partition
is restored to what it was before entering the parallel region. So when the hot
team is used for subsequent parallel regions, the master has lost this info.
This fix calls __kmp_partition_places to update only the master thread's place
partition in the spread case when there are no other changes to the hot team.

Patch by Terry Wilmarth

Differential Revision: http://reviews.llvm.org/D20539

llvm-svn: 270890