[llvm] [clang] [WIP][AMDGPU] Enable hostcall printf for OpenCL (PR #70932)

[Vikram Hegde via cfe-commits]

vikramRH wrote:

@b-sumner, @ssahasra , what are your thoughts about making the hostcall default throughout ?
Also I do not think splitting this into separate patches is feasible since changes are interdependent, however I could split changes into separate commits to make it easier to review.

https://github.com/llvm/llvm-project/pull/70932