Merge llvm-project release/19.x llvmorg-19.1.5-0-gab4b5a2db582
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