mesa/main: Make FEATURE_colortable follow feature conventions.

As shown in mfeatures.h, this allows users of colortab.h to work
without knowing if the feature is available.

src/mesa/main/texobj.c

@@ -29,9 +29,7 @@
 
 
 #include "mfeatures.h"
-#if FEATURE_colortable
 #include "colortab.h"
-#endif
 #include "context.h"
 #include "enums.h"
 #include "fbobject.h"
@@ -194,9 +192,7 @@ _mesa_delete_texture_object( GLcontext *ctx, struct gl_texture_object *texObj )
     */
    texObj->Target = 0x99;
 
-#if FEATURE_colortable
    _mesa_free_colortable_data(&texObj->Palette);
-#endif
 
    /* free the texture images */
    for (face = 0; face < 6; face++) {