Update minimum supported Rust version to 1.9.0

Susurrus · Susurrus · commit 98dcc8487a13 · 2017-02-26T12:57:13.000-08:00
diff --git a/README.md b/README.md
@@ -31,7 +31,7 @@ pub fn gethostname(name: &mut [u8]) -> Result<()>;
 ```
 
 ## Requirements
-Rust >= 1.7.0
+Rust >= 1.9.0
 
 ## Usage
 
