Zhihao Yuan noted that there were a few unneeded  statements.  Eliminated the unnecessary ones, and commented the ones that are there for non-obvious reasons such as to help things limp along in C++03 language mode.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@189039 91177308-0d34-0410-b5e6-96231b3b80d8