[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.

llvm-svn: 350571