mesa/main: Add support for GL_ARB_cull_distance (v2)

airlied:
v2: rename LowerClipDistance to LowerCombinedClipCullDistnace.
I don't think we want any other behaviour with any current hw.

Signed-off-by: Tobias Klausmann <tobias.johannes.klausmann@mni.thm.de>
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>

src/compiler/glsl/link_varyings.cpp

@@ -627,7 +627,7 @@ tfeedback_decl::init(struct gl_context *ctx, const void *mem_ctx,
     * class must behave specially to account for the fact that gl_ClipDistance
     * is converted from a float[8] to a vec4[2].
     */
-   if (ctx->Const.ShaderCompilerOptions[MESA_SHADER_VERTEX].LowerClipDistance &&
+   if (ctx->Const.ShaderCompilerOptions[MESA_SHADER_VERTEX].LowerCombinedClipCullDistance &&
        strcmp(this->var_name, "gl_ClipDistance") == 0) {
       this->lowered_builtin_array_variable = clip_distance;
    }

src/compiler/glsl/linker.cpp

@@ -4560,7 +4560,7 @@ link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
       if (!prog->LinkStatus)
 	 goto done;
 
-      if (ctx->Const.ShaderCompilerOptions[i].LowerClipDistance) {
+      if (ctx->Const.ShaderCompilerOptions[i].LowerCombinedClipCullDistance) {
          lower_clip_distance(prog->_LinkedShaders[i]);
       }
 

src/compiler/glsl/lower_clip_distance.cpp

@@ -42,7 +42,7 @@
  *
  * Since some hardware may not internally represent gl_ClipDistance as a pair
  * of vec4's, this lowering pass is optional.  To enable it, set the
- * LowerClipDistance flag in gl_shader_compiler_options to true.
+ * LowerCombinedClipCullDistance flag in gl_shader_compiler_options to true.
  */
 
 #include "glsl_symbol_table.h"