Upgrading libc dependencies

[bvssvni]

Announcement: https://users.rust-lang.org/t/the-libc-crate-is-now-at-v0-2-0/3509

This is for tracking issues with upgrading libc to 0.2.

• rand Bump to 0.4.0 rust-random/rand#81 Bump to 0.3.12 rust-random/rand#83
• freetype-sys uses libz-sys which depends on libc 0.1. Bump to 0.2.0 rust-lang/libz-sys#2
• glutin
• sdl2-sys
• sdl2
• glfw

Second phase:

• gl 0.4.0 release brendanzab/gl-rs#366 (fixed, but not published)
• glium Minor changes glium/glium#1348

[bvssvni]

glfw used "*" dependencies and needs a fix for existing code PistonDevelopers/glfw-rs#325

[bvssvni]

The challenge is to make sure that all the lower level libraries gets bumped before the higher ones. We don't have an exhaustive list of the lower libraries in Piston's ecosystem.

[bvssvni]

I want to get the gfx update yanked such that existing code will keep working. gfx-rs/gfx#826

[bvssvni]

An update in tempfile broke Glutin, so I want to get it yanked Stebalien/tempfile#17.

[bvssvni]

Piston core has now removed dependency on libc.

[bvssvni]

Done.