[OMPT] Fix parallel_data in implicit barrier-end

This is required to be NULL for implicit barriers at the end of a
parallel region. Noticed in review of D43191.

Differential Revision: https://reviews.llvm.org/D43308

git-svn-id: https://llvm.org/svn/llvm-project/openmp/trunk@325922 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed