llvmpipe, draw: increase shader cache limits

We're not particularly concerned with memory usage, if the tradeoff is
shader recompiles. And it's common for apps to have a lot of shaders
nowadays (and, since our shaders include a LOT of context state of course
we may create quite a bit more shaders even).
So quadruple the amount of shaders draw will cache (from 128 to 512).
For llvmpipe (fs shaders) quadruple the number of instructions, keep the
number of variants the same for now (only with very simple, non-texturing
shaders the variant limit could really be reached), and simplify the
definition, it's probably easier to just have one different definition
per branch...

Reviewed-by: Jose Fonseca <jfonseca@vmware.com>

src/gallium/auxiliary/draw/draw_private.h

@@ -103,7 +103,7 @@ struct vertex_header {
 
 
 /* maximum number of shader variants we can cache */
-#define DRAW_MAX_SHADER_VARIANTS 128
+#define DRAW_MAX_SHADER_VARIANTS 512
 
 /**
  * Private context for the drawing module.

src/gallium/drivers/llvmpipe/lp_limits.h

@@ -78,10 +78,8 @@
 /**
  * Max number of instructions (for all fragment shaders combined per context)
  * that will be kept around (counted in terms of llvm ir).
- * Note: the definition looks odd, but there's branches which use a different
- * number of max shader variants.
  */
-#define LP_MAX_SHADER_INSTRUCTIONS MAX2(256*1024, 512*LP_MAX_SHADER_VARIANTS)
+#define LP_MAX_SHADER_INSTRUCTIONS (2048 * LP_MAX_SHADER_VARIANTS)
 
 /**
  * Max number of setup variants that will be kept around.