[clang] [openmp] [OFFLOAD] Build DeviceRTL with SPIRV backend (PR #174675)

[Joseph Huber via cfe-commits]

https://github.com/jhuber6 commented:

Thanks for taking a first look at this, I won't be able to test the functional changes required to get the DeviceRTL working so this really helps.

https://github.com/llvm/llvm-project/pull/174675