[llvm] Add new llvm.dbg.declare_value intrinsic. (PR #168132)

[Jeremy Morse via llvm-commits]

https://github.com/jmorse commented:

NB, force push not desired due to githubs propensity to throw away review comments (insert here, griping about phab).

Thanks for removing the intrinsic bits; this soft LGTMs, final say from Apple folks I guess.

https://github.com/llvm/llvm-project/pull/168132