Add a deleted assignment operator for basic_ostream; LWG Issue #2067

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@188375 91177308-0d34-0410-b5e6-96231b3b80d8
Mark LWG Issue #2110 and #2113 as completed - they were already done

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@188378 91177308-0d34-0410-b5e6-96231b3b80d8