Merge llvm-project release/16.x llvmorg-16.0.4-0-gae42196bc493

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-16.0.4-0-gae42196bc493 (aka 16.0.4 release).

PR: 271047
MFC after: 1 month

Merge llvm-project 12.0.0 release

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12.0.0-0-gd28af7c654d8, a.k.a. 12.0.0 release.

PR: 255570
MFC after: 6 weeks

Regenerate ReStructuredText based manpages for llvm-project tools:

* bugpoint.1
* clang.1
* llc.1
* lldb.1
* lli.1
* llvm-ar.1
* llvm-as.1
* llvm-bcanalyzer.1
* llvm-cov.1
* llvm-diff.1
* llvm-dis.1
* llvm-dwarfdump.1
* llvm-extract.1
* llvm-link.1
* llvm-mca.1
* llvm-nm.1
* llvm-pdbutil.1
* llvm-profdata.1
* llvm-symbolizer.1
* llvm-tblgen.1
* opt.1

Add newly generated manpages for:

* llvm-addr2line.1 (this is an alias of llvm-symbolizer)
* llvm-cxxfilt.1
* llvm-objcopy.1
* llvm-ranlib.1 (this is an alias of llvm-ar)

Note that llvm-objdump.1 is an exception, as upstream has both a plain
.1 file, and a .rst variant. These will have to be reconciled upstream
first.

MFC after: 3 days

Update llvm tool manpages, and llvm-mca.1.

Regenerate llvm tools manpages, and add one for llvm-pbdutil.

Regenerate ReStructuredText based manpages for llvm-project tools:

* bugpoint.1
* clang.1
* llc.1
* lldb.1
* lli.1
* llvm-ar.1
* llvm-as.1
* llvm-bcanalyzer.1
* llvm-cov.1
* llvm-diff.1
* llvm-dis.1
* llvm-dwarfdump.1
* llvm-extract.1
* llvm-link.1
* llvm-mca.1
* llvm-nm.1
* llvm-pdbutil.1
* llvm-profdata.1
* llvm-symbolizer.1
* llvm-tblgen.1
* opt.1

Add newly generated manpages for:

* llvm-addr2line.1 (this is an alias of llvm-symbolizer)
* llvm-cxxfilt.1
* llvm-objcopy.1
* llvm-ranlib.1 (this is an alias of llvm-ar)

Note that llvm-objdump.1 is an exception, as upstream has both a plain
.1 file, and a .rst variant. These will have to be reconciled upstream
first.

MFC after: 3 days

Update llvm tool manpages, and llvm-mca.1.

Regenerate llvm tools manpages, and add one for llvm-pbdutil.