Auto merge of #1323 - jackpot51:patch-1, r=gnzlbg

Bump to 0.2.52

This will allow the crt-static feature to be utilized correctly on Redox, #1322

Cargo.toml

 [package]
 name = "libc"
-version = "0.2.51"
+version = "0.2.52"
 authors = ["The Rust Project Developers"]
 license = "MIT OR Apache-2.0"
 readme = "README.md"