That is a PHP extension. You will need to compile it before you can use it with PHP. The config.m4 file is the configuration file that would generate the makefile to compile the code.
If you are on Linux, configure and make are probably already installed. On windows you'd need to download those utilities and a C compiler.
As for using it on your free host, that is a no. You aren't going to be able to install an additional PHP plug-in and configure PHP to load it. You probably wouldn't even be able to do so with paid hosting unless you are on your own server.