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

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-17-init-19304-gd0b54bb50e51, the
last commit before the upstream release/17.x branch was created.

PR:		273753
MFC after:	1 month

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-15-init-15358-g53dc0f10787.

PR:		265425
MFC after:	2 weeks

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14-init-13186-g0c553cc1af2e.

PR:		261742
MFC after:	2 weeks