[OPENMP]Add call to __kmpc_push_target_tripcount() function.

[OPENMP]Add call to __kmpc_push_target_tripcount() function.

Each we create the target regions with the teams distribute inner
region, we can better estimate number of the teams required to execute
the target region. Function __kmpc_push_target_tripcount() is used for
purpose, which accepts device_id and the number of the iterations,
performed by the associated loop.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@350571 91177308-0d34-0410-b5e6-96231b3b80d8