Sync <net/if_types.h> with upstream.

Change-Id: I2c2ca47f5a21b78754c03deb3e9467ab79d9d033
Merge "Sync <net/if_types.h> with upstream."
<net/route.h> should include IPv6 too.

Change-Id: I866097d8468aa8f326117d072444ebbc2a690719
Merge "<net/route.h> should include IPv6 too."