Auto merge of #7060 - lzutao:zsh-complete-package, r=ehuss
Auto merge of #7060 - lzutao:zsh-complete-package, r=ehuss

_cargo: Make function style consistent

They are just white-space changes. I'm planning to bring back Zsh completion
for `-p` (package) option, which was disabled in #1713. This PR is the first
stepping stone towards that goal.

A disadvantageous is that I am just starting to learn Zsh completion system.
Guess how far can I go?

r? @ehuss

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