Fix compilation on FreeBSD.

Fix compilation on FreeBSD.

Without these two includes, compilation fails on FreeBSD with

/usr/include/net/if.h:265: error: field `ifru_addr' has incomplete type
/usr/include/net/if.h:266: error: field `ifru_dstaddr' has incomplete type
/usr/include/net/if.h:267: error: field `ifru_broadaddr' has incomplete type
/usr/include/net/if.h:299: error: field `ifra_addr' has incomplete type
/usr/include/net/if.h:300: error: field `ifra_broadaddr' has incomplete type
/usr/include/net/if.h:301: error: field `ifra_mask' has incomplete type
/usr/include/net/if.h:368: error: field `addr' has incomplete type
/usr/include/net/if.h:369: error: field `dstaddr' has incomplete type