a68: add import from .m68 file

a68: add import from .m68 file

Signed-off-by: Mohammad-Reza Nabipoor <mnabipoor@gnu.org>
gcc/algol68/ChangeLog

	* a68.h (a68_file_size): Changed to use file descriptor.
	(a68_file_read): Likewise.
	* a68-parser-scanner.cc (a68_file_size): Likewise.
	(a68_file_read): Likewise.
	(read_source_file): Adapt `a68_file_{size,read}'.
	(include_files): Likewise.
	* a68-lang.cc (a68_handle_option): Likewise.
	* a68-imports.cc (a68_find_export_data): Implement
	reading from module's .m68 file if available.

gcc/testsuite/ChangeLog

	* algol68/compile/modules/compile.exp (dg-data): New procedure
	for writing binary test data to disk.
	* algol68/compile/modules/program-m68-lp64.a68: New test which
	embeds binary module data.
	* algol68/compile/modules/program-m68-llp64.a68: Likewise.
	* algol68/compile/modules/program-m68-ilp32.a68: Likewise.
	* algol68/compile/modules/program-m68-lp64-be.a68: Likewise.
	* algol68/compile/modules/program-m68-llp64-be.a68: Likewise.