cobol: Add PUSH and POP to CDF.

Introduce cdf_directives_t class to centralize management of CDF
state. Move existing CDF state variables and functions into the new
class.

gcc/cobol/ChangeLog:

	PR cobol/120765
	* cdf.y: Extend grammar for new CDF syntax, relocate dictionary.
	* cdfval.h (cdf_dictionary): Use new CDF dictionary.
	* dts.h: Remove useless assignment, note incorrect behavior.
	* except.cc: Remove obsolete EC state.
	* gcobol.1: Document CDF in its own section.
	* genapi.cc (parser_statement_begin): Use new EC state function.
	(parser_file_merge): Same.
	(parser_check_fatal_exception): Same.
	* genutil.cc (get_and_check_refstart_and_reflen): Same.
	(get_depending_on_value_from_odo): Same.
	(get_data_offset): Same.
	(process_this_exception): Same.
	* lexio.cc (check_push_pop_directive): New function.
	(check_source_format_directive): Restrict regex search to 1 line.
	(cdftext::free_form_reference_format): Use new function.
	* parse.y: Define new CDF tokens, use new CDF state.
	* parse_ante.h (cdf_tokens): Use new CDF state.
	(redefined_token): Same.
	(class prog_descr_t): Remove obsolete CDF state.
	(class program_stack_t): Same.
	(current_call_convention): Same.
	* scan.l: Recognize new CDF tokens.
	* scan_post.h (is_cdf_token): Same.
	* symbols.h (cdf_current_tokens): Change current_call_convention to return void.
	* token_names.h: Regenerate.
	* udf/stored-char-length.cbl: Use new PUSH/POP CDF functionality.
	* util.cc (class cdf_directives_t): Define cdf_directives_t.
	(current_call_convention): Same.
	(cdf_current_tokens): Same.
	(cdf_dictionary): Same.
	(cdf_enabled_exceptions): Same.
	(cdf_push): Same.
	(cdf_push_call_convention): Same.
	(cdf_push_current_tokens): Same.
	(cdf_push_dictionary): Same.
	(cdf_push_enabled_exceptions): Same.
	(cdf_push_source_format): Same.
	(cdf_pop): Same.
	(cdf_pop_call_convention): Same.
	(cdf_pop_current_tokens): Same.
	(cdf_pop_dictionary): Same.
	(cdf_pop_enabled_exceptions): Same.
	(cdf_pop_source_format): Same.
	* util.h (cdf_push): Declare cdf_directives_t.
	(cdf_push_call_convention): Same.
	(cdf_push_current_tokens): Same.
	(cdf_push_dictionary): Same.
	(cdf_push_enabled_exceptions): Same.
	(cdf_push_source_format): Same.
	(cdf_pop): Same.
	(cdf_pop_call_convention): Same.
	(cdf_pop_current_tokens): Same.
	(cdf_pop_dictionary): Same.
	(cdf_pop_source_format): Same.
	(cdf_pop_enabled_exceptions): Same.

libgcobol/ChangeLog:

	* common-defs.h (cdf_enabled_exceptions): Use new CDF state.

(cherry picked from commit 3f59a1cac717f8af84e884e9ec0f6ef14e102e6e)