Auto merge of #7145 - alexcrichton:fix-typo, r=alexcrichton
Auto merge of #7145 - alexcrichton:fix-typo, r=alexcrichton

Fix a typo in an env var name

Not actually used yet in rust-lang/rust, but may as well try to get it
right on the first try.

vojtechkral/cargo,eminence/cargo,tshepang/cargo,rustyhorde/cargo,rust-lang/cargo,tsurai/cargo,tsurai/cargo,tshepang/cargo,rustyhorde/cargo,vojtechkral/cargo,rust-lang/cargo,nipunn1313/cargo,vojtechkral/cargo,tshepang/cargo,rust-lang/cargo,eminence/cargo,tsurai/cargo,eminence/cargo,tshepang/cargo,rust-lang/cargo,tsurai/cargo,rustyhorde/cargo,nipunn1313/cargo,vojtechkral/cargo,nipunn1313/cargo,rustyhorde/cargo,tsurai/cargo,eminence/cargo,nipunn1313/cargo