[OPENMP] Resolve lost LoopTripCnt for subsequent loops in same thread.

Remove loopTripCnt from threaded device stack after consuming it.
Added a libomptarget DP message to aid in future debugging and to
validate the added testcase, which only runs in Debug build.

Differential Revision: https://reviews.llvm.org/D64808


git-svn-id: https://llvm.org/svn/llvm-project/openmp/trunk@366349 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed