Comment 5 for bug 1416344

The proposed solution will not work. It will fail for librasync >= 1.0.0.
RS_MD4_SIG_MAGIC is a constant of the enumeration.
So #ifdef RS_MD4_SIG_MAGIC is always false.
The possible working solution could be based
on RS_DEFAULT_STRONG_LEN which exists for
librasync < 1.0.0 only.

#ifdef RS_DEFAULT_STRONG_LEN
  sm->sig_job = rs_sig_begin((size_t)blocklen,
                           (size_t)RS_DEFAULT_STRONG_LEN);
#else /* librasync >= 1.0.0 */
  sm->sig_job = rs_sig_begin((size_t)blocklen,
                           (size_t)8, RS_MD4_SIG_MAGIC);
#endif