MFC r276517:

MFC r276517:

Pull in r200010 from upstream libc++ trunk (by Marshall Clow):

  Rename some internal templates to avoid conflict with complier
  intrinsics. __is_constructible --> __libcpp_is_constructible,
  __is_nothrow_constructible --> __libcpp_is_nothrow_constructible, and
  __is_nothrow_assignable --> __libcpp_is_nothrow_assignable. No
  functionality change.

Pull in r206805 from upstream libc++ trunk (by Marshall Clow):

  Use compiler intrinsic __is_constructible if available

This should fix building parts of world with -std=c++11 enabled.

Reported by:	Oliver Hartmann <ohartman@zedat.fu-berlin.de>

git-svn-id: svn://svn.freebsd.org/base/stable/10@277299 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f