MFC r355940:

Move all sources from the llvm project into contrib/llvm-project.

This uses the new layout of the upstream repository, which was recently
migrated to GitHub, and converted into a "monorepo". That is, most of
the earlier separate sub-projects with their own branches and tags were
consolidated into one top-level directory, and are now branched and
tagged together.

Updating the vendor area to match this layout is next.

Move all sources from the llvm project into contrib/llvm-project.

This uses the new layout of the upstream repository, which was recently
migrated to GitHub, and converted into a "monorepo". That is, most of
the earlier separate sub-projects with their own branches and tags were
consolidated into one top-level directory, and are now branched and
tagged together.

Updating the vendor area to match this layout is next.

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
9.0.0 final release r372316.

Release notes for llvm, clang, lld and libc++ 9.0.0 are available here:

https://releases.llvm.org/9.0.0/docs/ReleaseNotes.html
https://releases.llvm.org/9.0.0/tools/clang/docs/ReleaseNotes.html
https://releases.llvm.org/9.0.0/tools/lld/docs/ReleaseNotes.html
https://releases.llvm.org/9.0.0/projects/libcxx/docs/ReleaseNotes.html

PR: 240629
MFC after: 1 month

Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
the upstream release_80 branch r355313 (effectively, 8.0.0 rc3). The
release will follow very soon, but no more functional changes are
expected.

Release notes for llvm, clang and lld 8.0.0 will soon be available here:
<https://releases.llvm.org/8.0.0/docs/ReleaseNotes.html>
<https://releases.llvm.org/8.0.0/tools/clang/docs/ReleaseNotes.html>
<https://releases.llvm.org/8.0.0/tools/lld/docs/ReleaseNotes.html>

PR: 236062
Relnotes: yes
MFC after: 1 month

Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
the upstream release_70 branch r348686 (effectively, 7.0.1 rc3). The
release will follow very soon, but no more functional changes are
expected.

Release notes for llvm, clang and lld 7.0.0 are available here:
<http://releases.llvm.org/7.0.0/docs/ReleaseNotes.html>
<http://releases.llvm.org/7.0.0/tools/clang/docs/ReleaseNotes.html>
<http://releases.llvm.org/7.0.0/tools/lld/docs/ReleaseNotes.html>

PR: 230240, 230355
Relnotes: yes
MFC after: 2 months

Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
4.0.0 (branches/release_40 296509). The release will follow soon.

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

Also note that as of 4.0.0, lld should be able to link the base system
on amd64 and aarch64. See the WITH_LLD_IS_LLD setting in src.conf(5).
Though please be aware that this is work in progress.

Release notes for llvm, clang and lld will be available here:
<http://releases.llvm.org/4.0.0/docs/ReleaseNotes.html>
<http://releases.llvm.org/4.0.0/tools/clang/docs/ReleaseNotes.html>
<http://releases.llvm.org/4.0.0/tools/lld/docs/ReleaseNotes.html>

Thanks to Ed Maste, Jan Beich, Antoine Brodin and Eric Fiselier for
their help.

Relnotes: yes
Exp-run: antoine
PR: 215969, 216008
MFC after: 1 month

Upgrade our copies of clang, llvm, lldb and compiler-rt to 3.8.0
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 will soon be available here:
<http://llvm.org/releases/3.8.0/docs/ReleaseNotes.html>
<http://llvm.org/releases/3.8.0/tools/clang/docs/ReleaseNotes.html>

Thanks to Ed Maste, Roman Divacky, Davide Italiano and Antoine Brodin
for their help.

Relnotes: yes

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

Create a branch for working on the clang/llvm/lldb 3.7.0 import.

(Copied from projects/clang-trunk, since that is now at the last
revision before upstream branched off 3.7.0.)

Update LLDB snapshot to upstream r241361

Notable upstream commits (upstream revision in parens):

- Add a JSON producer to LLDB (228636)
- Don't crash on bad DWARF expression (228729)
- Add support of DWARFv3 DW_OP_form_tls_address (231342)
- Assembly profiler for MIPS64 (232619)
- Handle FreeBSD/arm64 core files (233273)
- Read/Write register for MIPS64 (233685)
- Rework LLDB system initialization (233758)
- SysV ABI for aarch64 (236098)
- MIPS software single stepping (236696)
- FreeBSD/arm live debugging support (237303)
- Assembly profiler for mips32 (237420)
- Parse function name from DWARF DW_AT_abstract_origin (238307)
- Improve LLDB prompt handling (238313)
- Add real time signals support to FreeBSDSignals (238316)
- Fix race in IOHandlerProcessSTDIO (238423)
- MIPS64 Branch instruction emulation for SW single stepping (238820)
- Improve OSType initialization in elf object file's arch_spec (239148)
- Emulation of MIPS64 floating-point branch instructions (239996)
- ABI Plugin for MIPS32 (239997)
- ABI Plugin for MIPS64 (240123)
- MIPS32 branch emulation and single stepping (240373)
- Improve instruction emulation based stack unwinding on ARM (240533)
- Add branch emulation to aarch64 instruction emulator (240769)

Import LLDB as of upstream SVN 241361 (git 612c075f)