Modernize relational operators for shared_ptr and unique_ptr.  This includes adding support for nullptr, and using less<T*>.  Fixes http://llvm.org/bugs/show_bug.cgi?id=12056.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@151084 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed