Do not stream all zeros for gcda files.

gcc/ChangeLog:

	PR gcov-profile/95348
	* coverage.c (read_counts_file): Read only COUNTERS that are
	not all-zero.
	* gcov-dump.c (tag_function): Change signature from unsigned to
	signed integer.
	(tag_blocks): Likewise.
	(tag_arcs): Likewise.
	(tag_lines): Likewise.
	(tag_counters): Likewise.
	(tag_summary): Likewise.
	* gcov.c (read_count_file): Read all non-zero counters
	sensitively.

libgcc/ChangeLog:

	PR gcov-profile/95348
	* libgcov-driver.c (merge_one_data): Merge only profiles
	that are not of non-zero type.
	(write_one_data): Write counters only if there's one non-zero
	value.
	* libgcov-util.c (tag_function): Change signature from unsigned
	to int.
	(tag_blocks): Likewise.
	(tag_arcs): Likewise.
	(tag_counters): Likewise.
	(tag_summary): Likewise.
	(tag_lines): Read only if COUNTERS is non-zero.
	(read_gcda_file): Handle negative length for COUNTERS type.