glcpp: Add GL_ARB_conservative_depth #define.

Forgotten in the patch that enabled the extension.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
diff --git a/src/glsl/glcpp/glcpp-parse.y b/src/glsl/glcpp/glcpp-parse.y
index 0a35e88..9408304 100644
--- a/src/glsl/glcpp/glcpp-parse.y
+++ b/src/glsl/glcpp/glcpp-parse.y
@@ -1132,8 +1132,10 @@
 	   if (extensions->ARB_shader_texture_lod)
 	      add_builtin_define(parser, "GL_ARB_shader_texture_lod", 1);
 
-	   if (extensions->AMD_conservative_depth)
+	   if (extensions->AMD_conservative_depth) {
 	      add_builtin_define(parser, "GL_AMD_conservative_depth", 1);
+	      add_builtin_define(parser, "GL_ARB_conservative_depth", 1);
+	   }
 	}
 
 	language_version = 110;