[x86] Accept 'retn' as an alias to 'ret[lqw]'\'ret' (At&t\Intel)

Implement 'retn' simply by aliasing it to the relevant 'ret' instruction

Commit on behalf of coby

Differential Revision: https://reviews.llvm.org/D24346



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@282601 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed