Test for not existence of a negative loop (PR gcov-profile/90380).

Test for not existence of a negative loop (PR gcov-profile/90380).

2019-05-13  Martin Liska  <mliska@suse.cz>

	PR gcov-profile/90380
	* gcov.c (enum loop_type): Remove the enum and
	the operator.
	(handle_cycle): Assert that we should not reach
	a negative count.
	(circuit): Use loop_found instead of a tri-state loop_type.
	(get_cycles_count): Do not handle NEGATIVE_LOOP as it can't
	happen.

From-SVN: r271116