Auto merge of #4876 - MaloJaffre:flate2, r=alexcrichton
authorbors <bors@rust-lang.org>
Fri, 29 Dec 2017 22:13:32 +0000 (22:13 +0000)
committerbors <bors@rust-lang.org>
Fri, 29 Dec 2017 22:13:32 +0000 (22:13 +0000)
Upgrade flate2 crate to 1.0 in cargotest

I've missed this part in my previous PR, sorry.
Unblocks rust#46278.


Trivial merge