Update diffutils to rev 42 via SR 830967
    
    https://build.opensuse.org/request/show/830967
    by user jirislaby + dimstar_suse
    - gnulib-test-avoid-FP-perror-strerror.patch: avoid false-positive
      error in gnulib tests 'test-perror2' and 'test-strerror_r',
      visible on armv7l.