st/mesa: provide the null implementation of bounding box outputs in tcs

Until hardware appears (in a gallium driver) that can make use of the
TCS-outputted gl_BoundingBox, we just request that the variable gets
assigned as a regular patch variable.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>

docs/features.txt

@@ -262,7 +262,7 @@ GLES3.2, GLSL ES 3.2:
   GL_OES_draw_elements_base_vertex                      DONE (all drivers)
   GL_OES_geometry_shader                                DONE (i965/gen8+)
   GL_OES_gpu_shader5                                    DONE (all drivers that support GL_ARB_gpu_shader5)
-  GL_OES_primitive_bounding_box                         not started
+  GL_OES_primitive_bounding_box                         DONE (nvc0, radeonsi)
   GL_OES_sample_shading                                 DONE (i965, nvc0, r600, radeonsi)
   GL_OES_sample_variables                               DONE (i965, nvc0, r600, radeonsi)
   GL_OES_shader_image_atomic                            DONE (all drivers that support GL_ARB_shader_image_load_store)

docs/relnotes/12.1.0.html

@@ -59,6 +59,7 @@ Note: some of the new features are only available with certain drivers.
 <li>GL_KHR_texture_compression_astc_sliced_3d on i965</li>
 <li>GL_OES_copy_image on nv50, nvc0, r600, radeonsi, softpipe, llvmpipe</li>
 <li>GL_OES_geometry_shader on i965/gen8+</li>
+<li>GL_OES_primitive_bounding_box on nvc0, radeonsi</li>
 <li>GL_OES_texture_cube_map_array on i965/gen8+</li>
 </ul>
 

src/mesa/state_tracker/st_extensions.c

@@ -1210,4 +1210,7 @@ void st_init_extensions(struct pipe_screen *screen,
       extensions->ARB_texture_multisample &&
       extensions->ARB_gpu_shader5 &&
       extensions->EXT_shader_integer_mix;
+
+   extensions->OES_primitive_bounding_box = extensions->ARB_ES3_1_compatibility;
+   consts->NoPrimitiveBoundingBoxOutput = true;
 }