[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. This patch also
invalidates specifying target architectures with conflicting pointer
sizes.

Reviewers: jdoerfert

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

Tags: #OpenMP #Clang #LLVM

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