make the associative containers do the right thing for propogate_on_container_assignment. Fixes bug #29001. Tests are only for <map> right now - more complete tests will come when we revamp our allocator testing structure.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@279008 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed