[llvm] [SPIR-V] Emit SPIR-V bitcasts between source/expected pointer type (PR #69621)

[Nathan Gauër via llvm-commits]

https://github.com/Keenuts approved this pull request.

Others have said everything I had to say.
LGTM on my end then.

https://github.com/llvm/llvm-project/pull/69621