update readme

zilongshanren · zilongshanren · commit 0a94a790f8a9 · 2014-11-14T09:41:13.000+08:00
diff --git a/README.md b/README.md
@@ -35,6 +35,7 @@ brew update
 brew install git
 brew install cmake
 brew install m4
+brew install autoconf
 ```
 
 - If you want to build static libraries for iOS and Mac, you should install the latest version of XCode.  You should also install the `Command Line Tools` bundled with XCode.
