re PR c++/7228 (ICE when using member template and template function)
PR c++/7228
* cp-tree.h (CLASSTYPE_READONLY_FIELDS_NEED_INIT): Check that
lang_type structure exists before accessing field.
(SET_CLASSTYPE_READONLY_FIELDS_NEED_INIT): New macro.
(CLASSTYPE_REF_FIELDS_NEED_INIT): Similar.
(SET_CLASSTYPE_REF_FIELDS_NEED_INIT): New macro.
* class.c (check_field_decls): Use new macros.
* typeck2.c (process_init_constructor): Remove redundant check for
existence of lang_type structure.