mesa/compiler: add local_size_variable to shader_info

This will be used in api_validate.c in a following patch when we
switch to using gl_program pointers for the pipelines CurrentProgram
array.

Reviewed-by: Eric Anholt <eric@anholt.net>

src/compiler/shader_info.h

@@ -134,6 +134,8 @@ typedef struct shader_info {
       struct {
          unsigned local_size[3];
 
+         bool local_size_variable;
+
          /**
           * Size of shared variables accessed by the compute shader.
           */