xgettext: Define functions for the Ruby support.
* gettext-tools/src/xg-message.h (decide_is_format, intersect_range,
decide_do_wrap, decide_syntax_check): New declarations.
* gettext-tools/src/xg-message.c (decide_is_format, intersect_range,
decide_do_wrap, decide_syntax_check): New functions. extracted from
remember_a_message.
(remember_a_message): Invoke these functions.
