Auto merge of #7465 - alexcrichton:no-preserve, r=Eh2406
Auto merge of #7465 - alexcrichton:no-preserve, r=Eh2406

Disable preserving mtimes on archives

These are just wasted syscalls for our purposes, no need to issue
updates to the modification/creation/access times of files we unpack!

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