Modilfy the composite logic to two phases

Modilfy the composite logic to two phases

 We seperate the composite to two phases, firstly to
 select the shader according to source type and logic
 op, setting the right parameters. Then we emit the
 vertex array to generate the dest result.
 The reason why we do this is that the shader may be
 used to composite no only rect, trapezoid and triangle
 render function can also use it to render triangles and
 polygens. The old function glamor_composite_with_shader
 do the whole two phases work and can not match the
 new request.

Signed-off-by: Junyan He <junyan.he@linux.intel.com>