They are available, Im just lazy and havent gotten around to uploading it, its on the to-do list :P. Also planed to document how I build stuff, but same problem, just havent done it so far. Ill do one newer mesa version, then get to this, at least the bare minimum.
The "problem" is also testing if everyone pitches in a bit (no that theres a line of people willing to do so). Glide3 part of the driver is the one that got the most love and even that broke lots of things on win98 that are most likely just compiler related.
Also everyone has its own idea whats needs doing, that part will get tested, with a high chance it break smthing else.
If you read the history of commits, just for glide, some wanted to fix linux, some added 64bit support, lots of focus on winXp(makes sense at that time), some did general fixes, some did code cleanup, that effected the performance a bit. Whatever Koolsmoky pitched-in was amazing(not even kidding)... Its hard to maintain a project like that and guarantee everything will work.
Look your workflow. You jumped in, did some playing around, life got in the way, now you wanna do some more. Thats probably how most (again not that big of a line of people waiting), including me, will approach it.
Yea it all sounds great, have everything in a central repository, well documented and updated build procedures. But you have to be realistic here, the time investment required to do that. And someone dedicated to keep an eye what gets merged.