Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r261283:

Import libc++ 3.4 release. This contains a lot of bugfixes, and some
preliminary support for C++1y.

MFC r261604:

HEAD is not buildable for the past day. Commit a 'quick fix' in order to permit
buildworld to complete.

Reviewed by: theraven

MFC r261608:

Apply a cleaner solution for the sign warnings that can occur when
compiling libc++'s <locale> header with -Wsystem-headers on.

This has also been submitted upstream.

Reported by: asomers

MFC r261801:

An ABI incompatibility crept into the libc++ 3.4 import in r261283. It
was caused by upstream libc++ commit r194536, which aimed to make the
headers more standards-compliant, by making std::pair's copy constructor
trivial. Unfortunately, this could cause certain C++ applications using
shared libraries built against the previous version of libc++ to crash.

Fix the ABI incompatibility by making std::pair's copy constructor
non-trivial again.

Please note: Any C++ applications or shared libraries built with libc++
between r261283 and this revision should be recompiled.

Reported by: stefanf

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Add a c++/v1/tr1 include directory containing symlinks to all of the standard
headrs.

Lots of third-party code expects to find C++03 headers under tr1 because that's
where GNU decided to hide them. This should fix ports that expect them there.

MFC after: 1 week

After r253839, which modifies ld's behaviour to not automatically pull
in needed libraries, change libc++.so into a linker script, so it can
automatically pull in libcxxrt.so.

MFC after: 1 week

Fix broken macro checking in the libc++ Makefile, introduced in r241909.
This caused -std=c++0x not to be passed to the build by default.

Pointy hat to: dim
MFC after: 3 days

Allow building libc++ with any custom -std=xxx flag. Note that using
-std=gnu++98 will give a lot of warnings with clang, so please use
-std=c++0x or higher, or use NO_WERROR.

MFC after: 1 week

Add libcxxrt's objects (prefixing them with cxxrt_ to avoid collisions)
to libc++.a and libc++_p.a, to make static linking of C++ executables
with libc++ easier. This is similar to the approach used in libstdc++.

MFC after: 2 weeks

Install libcxxrt's C++ ABI and unwind headers. This is done in libc++'s
Makefile, so these headers go into the same destination directory as
libc++'s own headers, currently /usr/include/c++/v1.

MFC after: 3 days

Tabify libcxxrt and libc++'s Makefiles.

MFC after: 3 days

Make sure libgcc_s is finished building in _startup_libs before
building libcxxrt with high -j levels. The workaround in
libc++/Makefile isn't necessary once that race is solved.

Reviewed by: theravin

Import new versions of libcxxrt and libc++.
Please tests any C++ code you care about with -stdlib=libc++!

Approved by: dim (mentor)

Import libc++ / libcxxrt into base. Not build by default yet (use
MK_LIBCPLUSPLUS=yes to enable). This is a work-in-progress. It works for
me, but is not guaranteed to work for anyone else and may eat your dog.

To build C++ using libc++, add -stdlib=libc++ to your CXX and LD flags.

Bug reports welcome, bug fixes even more welcome...

Approved by: dim (mentor)