[OpenMP] Replace Clang's OpenMP RTL Definitions with OMPKinds.def

Summary: This changes Clang's generation of OpenMP runtime functions to use the types and functions defined in OpenMPKinds and OpenMPConstants. New OpenMP runtime function information should now be added to OMPKinds.def. This patch also changed the definitions of __kmpc_push_num_teams and __kmpc_copyprivate to match those found in the runtime.

Reviewers: jdoerfert

Reviewed By: jdoerfert

Subscribers: jfb, AndreyChurbanov, openmp-commits, fghanim, hiraditya, sstefan1, cfe-commits, llvm-commits

Tags: #openmp, #clang, #llvm

Differential Revision: https://reviews.llvm.org/D80222