On Mac OSX, Proxysql's dependencies are not fully satisfied by the tools included with the XCode/clang toolkit. The Proxysql build system needs to be told where to find non-system `curl` (and possibly `openssl`) libraries. Using the [Homebrew](https://brew.sh/) OSX package manager, dependencies can be installed and located on OSX like this:
```bash
brew install automake bzip2 cmake make git gpatch openssl curl