Merge llvm-project release/13.x llvmorg-13.0.0-rc2-43-gf56129fe78d5
This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13.0.0-rc2-43-gf56129fe78d5.
PR: 258209
(cherry picked from commit 69ade1e033e478ec426cafc0ec2104d672de294a)