i965: Enable ARB_shader_ballot on Gen8+

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

docs/features.txt

@@ -292,7 +292,7 @@ Khronos, ARB, and OES extensions that are not part of any OpenGL or OpenGL ES ve
   GL_ARB_sample_locations                               not started
   GL_ARB_seamless_cubemap_per_texture                   DONE (i965, nvc0, radeonsi, r600, softpipe, swr)
   GL_ARB_shader_atomic_counter_ops                      DONE (i965/gen7+, nvc0, radeonsi, softpipe)
-  GL_ARB_shader_ballot                                  DONE (nvc0, radeonsi)
+  GL_ARB_shader_ballot                                  DONE (i965/gen8+, nvc0, radeonsi)
   GL_ARB_shader_clock                                   DONE (i965/gen7+, nv50, nvc0, radeonsi)
   GL_ARB_shader_draw_parameters                         DONE (i965, nvc0, radeonsi)
   GL_ARB_shader_group_vote                              DONE (i965, nvc0, radeonsi)

docs/relnotes/17.2.0.html

@@ -46,6 +46,7 @@ Note: some of the new features are only available with certain drivers.
 <ul>
 <li>GL_ARB_bindless_texture on radeonsi</li>
 <li>GL_ARB_post_depth_coverage on nvc0 (GM200+)</li>
+<li>GL_ARB_shader_ballot on i965/gen8+</li>
 <li>GL_ARB_shader_group_vote on i965 (with a no-op vec4 implementation)</li>
 <li>GL_ARB_shader_viewport_layer_array on nvc0 (GM200+)</li>
 <li>GL_AMD_vertex_shader_layer on nvc0 (GM200+)</li>

src/mesa/drivers/dri/i965/intel_extensions.c

@@ -271,6 +271,7 @@ intelInitExtensions(struct gl_context *ctx)
 
    if (brw->gen >= 8) {
       ctx->Extensions.ARB_gpu_shader_int64 = true;
+      ctx->Extensions.ARB_shader_ballot = true; /* requires ARB_gpu_shader_int64 */
       ctx->Extensions.ARB_ES3_2_compatibility = true;
    }