This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project release/19.x llvmorg-19.1.5-0-gab4b5a2db582,
a.k.a. 19.1.5 release.

PR:		280562
MFC after:	3 days

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project release/19.x llvmorg-19.1.2-0-g7ba7d8e2f7b6,
a.k.a. 19.1.2 release.

PR:		280562
MFC after:	1 month

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project release/19.x llvmorg-19.1.1-0-gd401987fe349,
a.k.a. 19.1.1 release.

PR:		280562
MFC after:	1 month

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project release/19.x llvmorg-19.1.0-0-ga4bf6cd7cfb1,
a.k.a. 19.1.0 release.

PR:		280562
MFC after:	1 month

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project release/19.x llvmorg-19.1.0-rc4-0-g0c641568515a.

PR:		280562
MFC after:	1 month

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project release/19.x llvmorg-19.1.0-rc3-0-g437434df21d8.

PR:		280562
MFC after:	1 month

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project release/19.x llvmorg-19.1.0-rc2-0-gd033ae172d1c.

PR:		280562
MFC after:	1 month

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-19-init-18630-gf2ccf80136a0, the
last commit before the upstream release/19.x branch was created.

PR:		280562
MFC after:	1 month

  [Parallel] Revert sequential task changes

  https://reviews.llvm.org/D148728 introduced `bool Sequential` to unify
  `execute` and the old `spawn` without argument. However, sequential
  tasks might be executed by any worker thread (non-deterministic),
  leading to non-determinism output for ld.lld -z nocombreloc (see
  https://reviews.llvm.org/D133003).

  In addition, the extra member variables have overhead.
  This sequential task has only been used for lld parallel relocation
  scanning.

  This patch restores the behavior before https://reviews.llvm.org/D148728 .

  Fix #105958

  Pull Request: https://github.com/llvm/llvm-project/pull/109084

This fixes the non-reproducibility we had noticed when linking our EFI
loaders, and for which we committed a workaround in f5ce3f4ef562.

MFC after:	3 days

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project release/18.x llvmorg-18.1.6-0-g1118c2e05e67.

PR:		276104
MFC after:	3 days