Merge llvm-project main llvmorg-18-init-16003-gfc5f51cf5af4
This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-18-init-16003-gfc5f51cf5af4.
PR: 276104
MFC after: 1 month
(cherry picked from commit 647cbc5de815c5651677bf8582797f716ec7b48d)