[OpenMP] Replace OpenMP RTL Functions With OMPIRBuilder and OMPKinds.def

Summary:
Replace the OpenMP Runtime Library functions used in CGOpenMPRuntimeGPU
for OpenMP device code generation with ones in OMPKinds.def and use
OMPIRBuilder for generating runtime calls. This allows us to
consolidate more OpenMP code generation into the OMPIRBuilder. Future
additions to the GPU runtime functions should now go in OMPKinds.def

Reviewers: jdoerfert

Subscribers: aaron.ballman cfe-commits guansong llvm-commits sstefan1 yaxunl

Tags: #OpenMP #LLVM #clang

Differential Revision: https://reviews.llvm.org/D88430