[clang] [HIP] Do not apply 'externally_initialized' to constant device variables (PR #182157)

[Joseph Huber via cfe-commits]

jhuber6 wrote:

There should be cases of `__constant__` without const, and the changes shouldn't be able to modify those because it's an attribute and not a qualifier on the type. The test files I modified already do not touch `__device__`, those are retained. There's lots of CodeGenCUDA tests w/ `__constant__` that weren't affected by this PR.

https://github.com/llvm/llvm-project/pull/182157