parameter, not an optional string. Also, call new convenience
function that takes res_id's.
* resrc.c (define_control): missing text means zero-length string,
not zero ID.
(define_icon_control): New.
* windres.h: declare define_icon_control.
all returns with MAYBE_RETURN
(MAYBE_RETURN): new, implement the suppression by returning
IGNORED_TOKEN as needed.
(cpp_line): remember which file we're in, mark data from included
*.h files for suppression.
* rcparse.y (input): allow IGNORED_TOKEN outside of known constructs
