Auto merge of #3047 - alexcrichton:update-libz, r=alexcrichton
authorbors <bors@rust-lang.org>
Fri, 26 Aug 2016 21:43:13 +0000 (14:43 -0700)
committerGitHub <noreply@github.com>
Fri, 26 Aug 2016 21:43:13 +0000 (14:43 -0700)
Update libz-sys to 1.0.6

Fixes a build error on OSX

Closes #3037


Trivial merge