Tag Apachesolr index table select queries to allow other modules to alter them.

I have a requirement where I by I don't want to index content older than 10 years. While I can add my own callback to evaluate if a node should be indexed or not, the apachesolr module will still needlessly evaluate all the content older than 10 years. It also means the apachesolr module can't determine how much content should be indexed and compare that to how much actually is.

If there were tags added to the select queries used, that would allow me to prevent the module from even considering indexing content older than 10 years.

Attached is a patch I currently use to achieve this.