Add macOS development requirements about libffi-sys.

DEVELOPMENT.md

@@ -30,6 +30,10 @@ RustPython requires the following:
       from the [Python website](https://www.python.org/downloads/), or
       using a third-party distribution, such as 
       [Anaconda](https://www.anaconda.com/distribution/).
+- [macOS] In case of libffi-sys compilation error, make sure autoconf, automake,
+   libtool are installed
+    - To install with [Homebrew](https://brew.sh), enter 
+      `brew install autoconf automake libtool`
 - [Optional] The Python package, `pytest`, is used for testing Python code
   snippets. To install, enter `python3 -m pip install pytest`.