Auto merge of #3988 - sdroege:bench-all, r=alexcrichton
authorbors <bors@rust-lang.org>
Tue, 2 May 2017 14:12:33 +0000 (14:12 +0000)
committerbors <bors@rust-lang.org>
Tue, 2 May 2017 14:12:33 +0000 (14:12 +0000)
Add support for benchmarking all members of a workspace with "bench --all"

Same behaviour as "build --all" and others.

See https://github.com/rust-lang/cargo/issues/2878#issuecomment-298302043


Trivial merge