Fix riscv64 build
    
    It currently fails with:
    
      RPM build errors:
      error: File not found: .../usr/lib/binfmt.d/qemu-riscv32-static.conf
    
    This is caused by the qemu-binfmt-conf.sh script assuming that
    all riscv64 CPUs can natively run riscv32 applications, which
    is actually not the case in practice.
    
    Backport a few patches from upstream. Once those have been
    applied, the script can be convinced to behave correctly, i.e.
    generate the file that until now was missing.
    
    Signed-off-by: Andrea Bolognani <abologna@redhat.com>