defined prf_ra{} outside in6_prflags to be friendly with c++. From:	  Pavlin Radoslavov <pavlin@icir.org>
defined prf_ra{} outside in6_prflags to be friendly with c++.
From:	  Pavlin Radoslavov <201f1b8540b3875e84c284b242f7385b2d2c2472@icir.org>

MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame