This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-18-init-18359-g93248729cfae, the
last commit before the upstream release/18.x branch was created.
PR: 276104
MFC after: 1 month
(cherry picked from commit 7a6dacaca14b62ca4b74406814becb87a3fefac0)
