MFC 316644:

Trying to be more compatible with Linux if.h definitions:

• renaming l_ifreq::ifru_metric to l_ifreq::ifru_ivalue;
• adding a definition for ifr_ifindex which points to l_ifreq::ifru_ivalue.

A quick search indicates that Linux already got the above changes since 2.1.14.

Reviewed by: kib, marcel, dchagin