MFC r241903:

MFC r241903:

  Import libc++ trunk r165949.  Among other improvements and bug fixes,
  this has many visibility problems fixed, which should help with
  compiling certain ports that exercise C++11 mode (i.e. Firefox).

  Also, belatedly add the LICENSE.TXT and accompanying CREDITS.TXT files,
  which are referred to in all the source files.

MFC r241907:

  Fix two -Wsystem-header warnings in libc++ that were exposed by the new
  ATF import.  These have also been sent upstream.

git-svn-id: svn://svn.freebsd.org/base/stable/9@243376 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f