Update obfs4proxy to 0.0.5, remove the old go.net code.
New tag for socks5 and to change the upstream dependency.
The new tag gets:
- SOCKS5 support, for obfs4proxy's PTs, separate from #12535 (moved).
- Changed from
code.google.com/p/go.net
togolang.org/x/net
for a dependency.
The gitian descriptor already handles pulling down the required code from the new location thanks to #15265 (moved), so all that's left is to remove the mentions of the old code and stop fetching the tarball from my people.tp.o directory, and updating the tag.