Enable the LLVM_ENABLE_RUNTIMES=flang-rt build of the Fortran runtime for the amdgpu-offload-* buildbots. This pre-population cmake cache files is referred to by the llvm-zorg annotated builder factory [script](872f477610/zorg/buildbot/builders/annotated/amdgpu-offload-cmake.py (L26)). The corresponding change in llvm-zorg is llvm/llvm-zorg#402 This reverts commite296fb8ff6. The worker of amdgpu-offload-rhel-8-cmake-build-only has been updated with a newer version of Ninja that supports Fortran.