MFC r350360:

Merge libcxxrt master f96846efbfd508f66d91fcbbef5dd808947c7f6d.

Interesting fixes:
f96846e Fix std::size_t -> size_t to unbreak build against libc++ 6.0.0
6f4cfa2 Fix the uncaught exception count with rethrowing (PR 239265)
db54f53 Added C++14-specific operator delete (#47)

PR: 239265

MFC r328305: libcxxrt: Move mangled symbols out of extern "C++" in Version.map

r260553 added a number of mangled C++ symbols to Version.map inside of
an existing `extern "C++"` block.

ld.bfd 2.17.50 treats `extern "C++"` permissively and will match both
mangled and demangled symbols against the strings in the version map
block. ld.lld interprets `extern "C++"` strictly, and matches only
demangled symbols.

I believe lld's behaviour is correct. Contemporary versions of ld.bfd
also behave as lld does, so move the mangled symbols out of the
`extern "C++"` block.

PR: 225128, 185663
Sponsored by: The FreeBSD Foundation

MFC r314061:

Add __int128-related symbols to libcxxrt's version map. Put these into
the same CXXABI verions as recent libstdc++.

Note that __int128 types are only available on arches where long long is
128 bit wide.

Noticed by: harti

MFC r314104:

Surround any unmangled C++ names in libcxxrt's version map with 'extern
"C++"', otherwise ld refuses to make the symbols global in the final
library. This causes the __int128-related symbols to go missing when
the library is stripped during installation.

Helpful hints: emaste

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

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

libcxxrt: correct mangled "typeinfo name" symbols in Version.map

r260553 added missing C++ typinfos to libcxxrt's version script.
It appears that a number of duplicate mangled symbols were added due to
a cut and paste error. Switch the second instances to _ZTS*,
typeinfo name for *.

Found by lld, which produces an error or warning for duplicate symbols.

Reviewed by: dim
Approved by: re (gjb)
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D7011

Upgrade our copies of clang, llvm, lldb, compiler-rt and libc++ to 3.7.0
release.

Please note that from 3.5.0 onwards, clang, llvm and lldb require C++11
support to build; see UPDATING for more information.

Release notes for llvm and clang can be found here:
<http://llvm.org/releases/3.7.0/docs/ReleaseNotes.html>
<http://llvm.org/releases/3.7.0/tools/clang/docs/ReleaseNotes.html>

Thanks to Ed Maste, Andrew Turner and Antoine Brodin for their help.

Exp-run: antoine
Relnotes: yes

Add __cxa_deleted_virtual to libcxxrt's version map.

This symbol can sometimes be emitted by clang++, and was not yet
exported from libcxxrt. Attempt to be compatible with libsupc++ by
using the same CXXABI_1.3.6 symbol version.

Reported by: yuri@rawbw.com
PR: 200863
Reviewed by: emaste
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D2850

Add support for __cxa_throw_bad_array_new_length in libcxxrt

It is required for use with newer g++49

Differential Revision: https://reviews.freebsd.org/D982
Reviewed by: theraven
Approved by: theraven
MFC after: 3 weeks

Add missing C++11 typeinfos to the libcxxrt version script.

PR: 185663
MFC after: 1 week

Add several missing symbols to libcxxrt's symbol version map, and remove
a few duplicates. This should fix building world with -stdlib=libc++
after r246028.

Submitted by: Yamaya Takashi <yamayan@kbh.biglobe.ne.jp>
MFC after: 1 week
X-MFC-With: r246028

Fix some symbol version mismatches between libstdc++ and libsupc++/libcxxrt
that were causing the runtime and STL libraries to see different versions of
various classes and functions when libstdc++ is used as a filter.

Note: This changes the ABI for libcxxrt, but libcxxrt is currently only in
-STABLE for testing and is not used by anything unless explicitly enabled by
the end user. No default compiler configurations use it.

libc++ will need to be recompiled after this change. make buildworld will do
this automatically, but make in lib/libc++ will not necessarily work unless the
new libcxxrt is installed first.

PR: kern/171610, stand/175453
Reviewed by: kib
MFC after: 1 week

Clean up some symbol versions for libsupc++ / libcxxrt.

MFC after: 1 week
Reviewed by: kan

Import new version of libcxxrt. Now works correctly with libobjc2 to implement
the unified exception model for Objective-C++.

Approved by: dim (mentor)

Add symbol versioning to libcxxrt.

Approved by: dim (mentor)