servo
make gleam no_std compatible
See https://github.com/brendanzab/gl-rs/pull/530 - I need gleam to be no_std because I have some crates that use the Rc<dyn Gl> type (but don't actually call any GL functions), so it would be good if this crate is no_std, so that my crates can be no_std, too. I've added very simple CString and CStr wrappers, so that the crate can be used on libcore.
This is a preparation to get webrender/swgl to run on embedded hardware (should be possible, since there's no actual system dependency).
Note that the Cargo.toml currently points to my fork, this needs to be updated once a new version of gl-rs is published.
:umbrella: The latest upstream changes (presumably #222) made this pull request unmergeable. Please resolve the merge conflicts.
