analyzer: better logging of event creation

analyzer: better logging of event creation

gcc/analyzer/ChangeLog:
	* checker-path.cc (checker_event::debug): New.
	(checker_path::add_event): Move here from checker-path.h.  Add
	logging.
	* checker-path.h (checker_event::debug): New decl.
	(checker_path::checker_path): Add logger param.
	(checker_path::add_event): Move definition from here to
	checker-path.cc.
	(checker_path::m_logger): New field.
	* diagnostic-manager.cc
	(diagnostic_manager::emit_saved_diagnostic): Pass logger to
	checker_path ctor.
	(diagnostic_manager::add_events_for_eedge): Log scope when
	processing a run of stmts.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>