piros/tor: Code added to Tor to support PIR-based onion service descriptor lookups @ a6eaa121e47625f9e9195b87c18f85d1307ee409

Nick Mathewson df87812b41 Merge remote-tracking branch 'teor/fallbacks-20161219'		7 lat temu
..
.dummy	df76da0f3b Add a .dummy file in the changes directory to stop git from removing it	9 lat temu
fallbacks-201612	53ec087450 Avoid an error in the fallback script when a fallback doesn't have any uptime	7 lat temu