gcov: print total_lines summary for all files.

gcov: print total_lines summary for all files.

gcc/ChangeLog:

2020-04-17  Martin Liska  <mliska@suse.cz>

	PR gcov-profile/94636
	* gcov.c (main): Print total lines summary at the end.
	(generate_results): Expect file_name always being non-null.
	Print newline after intermediate file is printed in order to align with
	what we do for normal files.