Apply compiler-rt fix for building with earlier versions of clang
Merge commit 18efa420da5f from llvm git (by Brooks Davis)
compiler-rt: Allow build without __c11_atomic_fetch_nand Don't build atomic fetch nand libcall functions when the required compiler builtin isn't available. Without this compiler-rt can't be built with LLVM 13 or earlier. Not building the libcall functions isn't optimal, but aligns with the usecase in FreeBSD where compiler-rt from LLVM 14 is built with an LLVM 13 clang and no LLVM 14 clang is built. Reviewed By: efriedma Differential Revision: https://reviews.llvm.org/D126710
MFC after: 3 days
(cherry picked from commit cfefd16d5721f5bb89506df7d2bb9e18f60b034a)