glapi: add entry points for GL_ARB_compute_variable_group_size

v2: - correctly sort that new extension (Ian)
    - fix up the comment (Ian)

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
diff --git a/src/mesa/main/compute.c b/src/mesa/main/compute.c
index b71430f..b052bae 100644
--- a/src/mesa/main/compute.c
+++ b/src/mesa/main/compute.c
@@ -60,3 +60,11 @@
 
    ctx->Driver.DispatchComputeIndirect(ctx, indirect);
 }
+
+void GLAPIENTRY
+_mesa_DispatchComputeGroupSizeARB(GLuint num_groups_x, GLuint num_groups_y,
+                                  GLuint num_groups_z, GLuint group_size_x,
+                                  GLuint group_size_y, GLuint group_size_z)
+{
+
+}