Merge llvm-project release/16.x llvmorg-16.0.6-0-g7cbf1a259152

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-16.0.6-0-g7cbf1a259152 (aka 16.0.6 release).

PR: 271047
MFC after: 1 month

Merge llvm-project main llvmorg-12-init-17869-g8e464dd76bef

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12-init-17869-g8e464dd76bef, the last commit before the
upstream release/12.x branch was created.

PR: 255570
MFC after: 6 weeks

Regenerate config and version headers.

Merge llvm, clang, lld, lldb, compiler-rt and libc++ r306325, and update
build glue.

Initial update of clang/llvm build glue, for building just a minimal
clang executable.

Initial updates to llvm/clang build glue.

Regenerate config and version headers.

Initial update of clang/llvm build glue, for building just a minimal
clang executable.

Initial updates to llvm/clang build glue.