Merge of r181328

Mention SystemZ in the release notes


git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_33@181427 91177308-0d34-0410-b5e6-96231b3b80d8
Merge of r181431

Add SystemZ feats to CodeGenerator.rst


git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_33@181432 91177308-0d34-0410-b5e6-96231b3b80d8
Merge of r181434

Add myself as SystemZ code owner


git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_33@181435 91177308-0d34-0410-b5e6-96231b3b80d8