vrend: rework handling of alpha and luminance formats
- format: drop ALPHA 16F and 32F emulation on core
- formats: Unify handling of LA formats
- vrend: rework the TBO swizzle shader key evaluation
- vrend: Mark shader dirty when we bind a TBO
- vrend: Add mapping for Alpha 16F and Alpha 32F TBO format
This fixes a few piglits and also the use of a compatibility profile on the host.
Edited by Gert Wollny