Add a default mods-available spx.ini entry on install

[codebymikey]

On doing an install, it'd be nice if it could create a /etc/php/$php_version/mods-available/spx.ini file if it doesn't already exist, with a default entry of something along the lines of:

; configuration for php spx module
; priority=20
extension=spx.so

That way phpenmod spx and phpdismod spx can be used to easily switch it off/on.

[NoiseByNorthwest]

It looks like phpenmod is specific to debian-based distros and the path /etc/php/$php_version/mods-available/spx.ini is not portable either.
So it may best fixed in a debian-specific package.