Remove label_or_decl
Remove label_or_decl

The only use of this function can be rewritten in terms of
is_label (if one other use of that one are a bit amended).

mirror/tinycc,code4game/tinycc,andreiw/tinycc,mirror/tinycc,avih/tinycc,avih/tinycc,mingodad/tinycc,mirror/tinycc,avih/tinycc,mingodad/tinycc,andreiw/tinycc,mingodad/tinycc,mirror/tinycc,code4game/tinycc,mingodad/tinycc,andreiw/tinycc,avih/tinycc,code4game/tinycc