mesa: remove old comments

Note: the default value for EmitCondCodes is FALSE.  This means the GLSL
compiler will emit code like this:

SEQ TEMP[0].x, A, B;
IF TEMP[0].x;
   ...
ENDIF

But if EmitCondCodes is TRUE, condition codes will be used instead:

SEQ.C TEMP[0].x, A, B;
IF (NE.xxxx);
   ...
ENDIF

src/mesa/shader/shader_api.c

@@ -406,7 +406,7 @@ _mesa_init_shader_state(GLcontext * ctx)
     * are generated by the GLSL compiler.
     */
    ctx->Shader.EmitHighLevelInstructions = GL_TRUE;
-   ctx->Shader.EmitCondCodes = GL_FALSE;/*GL_TRUE;*/ /* XXX probably want GL_FALSE... */
+   ctx->Shader.EmitCondCodes = GL_FALSE;
    ctx->Shader.EmitComments = GL_FALSE;
    ctx->Shader.Flags = get_shader_flags();
 }