Mark LWG issue 2218 as complete.

LWG issue 2218 relaxes a restriction on how containers can call
Alloc::construct(...) and Alloc::destroy(...). There is nothing new to test.


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@271477 91177308-0d34-0410-b5e6-96231b3b80d8