diagnostics: disable localization of events in selftest paths [PR115203]

diagnostics: disable localization of events in selftest paths [PR115203]

gcc/ChangeLog:
	PR analyzer/115203
	* diagnostic-path.h
	(simple_diagnostic_path::disable_event_localization): New.
	(simple_diagnostic_path::m_localize_events): New field.
	* diagnostic.cc
	(simple_diagnostic_path::simple_diagnostic_path): Initialize
	m_localize_events.
	(simple_diagnostic_path::add_event): Only localize fmt if
	m_localize_events is true.
	* tree-diagnostic-path.cc
	(test_diagnostic_path::test_diagnostic_path): Call
	disable_event_localization.

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