* gengtype.h: Remove all type definitions to gengtype.c; leave
	only definitions of options_p, type_p, and pair_p as opaque
	pointers.  Update prototypes.
	* gengtype.c: Many type definitions moved here from gengtype.h.
	Consolidate type definitions at the top of the file.
	(xvasprintf): Delete.
	(xasprintf): Make static.
	(create_nested_pointer_option): Add 'next' parameter.
	(create_field_all, create_field_at): New functions.
	(create_field): Now a thin wrapper around create_field_all.
	(create_optional_field): Rename create_optional_field_ and add
	line argument.  Original name is now a macro which supplies
	__LINE__.
	(oprintf): Use vsnprintf directly.
	(close_output_files): Use fatal rather than perror/exit.
	(note_def_vec, note_def_vec_alloc): Use create_field_at.
	(main): Set progname.  Don't use exit.
	* gengtype-yacc.y (struct_fields): Use create_field_at.
	(option, optionseqopt): Delete.
	(optionseq): Consolidate productions from option here so we
	can use the first argument to create_option.

From-SVN: r123233