Merge llvm-project release/18.x llvmorg-18.1.3-0-gc13b7485b879
This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project release/18.x llvmorg-18.1.3-0-gc13b7485b879.
PR: 276104
MFC after: 1 month
(cherry picked from commit 439352ac8257c8419cb4a662abb7f260f31f9932)