[llvm] [SPARC][IAS] Add `illtrap` alias for `unimp` (PR #105928)

[Sergei Barannikov via llvm-commits]

s-barannikov wrote:

> I'm slightly leaning towards using Solaris behavior in this particular case but in any case either choice is okay by me.

I'm not sure we should be looking at the Solaris toolchain at all. llvm-based toolchain isn't a drop-in replacement for it.


https://github.com/llvm/llvm-project/pull/105928