Simplify the MCInst operator iterator declaration.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179541 91177308-0d34-0410-b5e6-96231b3b80d8
Fix a typo in comment.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179542 91177308-0d34-0410-b5e6-96231b3b80d8