Mark LWG issues 2868, 2872, and 2890 as complete. There's nothing we need to do for them.
Mark LWG issues 2868, 2872, and 2890 as complete. There's nothing we need to do for them.

git-svn-id: 756ef344af921d95d562d9e9f9389127a89a6314@297758 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/libcxx,llvm-mirror/libcxx,llvm-mirror/libcxx,llvm-mirror/libcxx,llvm-mirror/libcxx