* bug 24268: avoid assertion after reporting error for invalid call to builtin_debug

* bug 24268, remove duplicated warning tag in lexer messages

* bug 24268, fix spelling in array element designator message

* bug 24268, unify 'consider adding option ...' messages

* bug 24268, add spacing for icbi operands

* bug 24268, uniform use of Ignored_attributes class for identical warnings

* bug 24268, unify message for 'assignment to const type' to error from error/fatal error

* bug 24268, in handcrafted.messages, "a xxx have been recognized" -> "a xxx has been recognized"