Despite the name, most of resolv_private.h is actually in glibc; it's just
that there it's tucked away in libresolv whereas we have it in libc.
Change-Id: Ibcf6603f1141ffd2661cee0bffa83052d4f9e549
Calling connect() will erase the mark set by the host resolver code because the
explicitlySelected bit of the Fwmark isn't set. It's by design that the
explicitlySelected bit isn't set as this facilitates falling through to other
routing rules if the selected network doesn't provide a route to the DNS server
as may be the case with VPNs.
Change-Id: I60ba7c754194ead97df3ac6a6c5b3db1f446dac8
Replace iface cache key with netid.
Replace _mark with netid.
Mark sockets used to test IPv4/IPv6 support as well as sockets
used to determine source address for rfc6724 sort.
Remove pid/uid mappings (functionality moved to system/netd).
Do not create resolv_cache when it does not exist, but rather only
when DNS configuration is supplied.
Clean up unused functions.
Change-Id: I9ccfda2902cc0943e87c9bc346ad9a2578accdab
