Auto merge of rust-lang#721 - fitzgen:bump-to-0.25.2, r=emilio

Bump to version 0.25.2

Need to publish a new version so I can rely on the MacOS mangling fix for my smup branch.

r? @emilio

Auto merge of rust-lang#636 - servo:clang_args, r=emilio

Add Builder::clang_args (plural)

Use `AsRef<str>` rather than `Into<String>` because `&&str` (what you get when iterating `&[&str]`) does not implement the latter.