apache-mpm-{event,worker}: add version var for new template lexer.

I'm writing a new lexer for xbps-repo-checkvers, and I want to avoid having to process sourced templates.

Here's what I need:

1. Every template just has to have a:
   a) pkgname,
   b) version,
   c) revision

The two apache-mpm-{event,worker} ones were the only ones that didn't have a 'version' variable.  Even though they source the 'apache' template, I still want the version variable in them.