[llvm] [AMDGPU] Add a regression test for -mattr=dumpcode (PR #116982)

[Jay Foad via llvm-commits]

jayfoad wrote:

This test failed on a big-endian host: https://lab.llvm.org/buildbot/#/builders/42/builds/3253

#127064 works around this.

https://github.com/llvm/llvm-project/pull/116982