The uniforms for the alpha test reference value and point size on
GLES2 are updating using similar code. This generalizes the code so
that there is a static array of predefined builtin uniforms which
contains the uniform name, a pointer to a function to get the value
from the pipeline, a pointer to a function to update the uniform and a
flag representing which CoglPipelineState change affects the
uniform. The uniforms are then updated in a loop. This should simplify
adding more builtin uniforms.
e778018d0d