[OpenMP][libomptarget] Enable the compilation of multiple bc libraries for runtime inlining

Summary:
Different NVIDIA GPUs support different compute capabilities. To enable the inlining of runtime functions and the best performance on different generations of NVIDIA GPUs, a bc library for each compute capability needs to be compiled. The same compiler build will then be usable in conjunction with multiple generations of NVIDIA GPUs.
To differentiate between versions of the same bc lib, the output file name will contain the compute capability ID.
Depends on D14254

Reviewers: Hahnfeld, hfinkel, carlo.bertolli, caomhin, ABataev, grokos

Reviewed By: Hahnfeld, grokos

Subscribers: guansong, mgorny, openmp-commits

Differential Revision: https://reviews.llvm.org/D41724

llvm-svn: 324904