diagnostics: fix <title> of experimental-html output [PR116792]

diagnostics: fix <title> of experimental-html output [PR116792]

Add a new vfunc diagnostic_output_format::set_main_input_filename
so that we can separate setting the <title> of HTML output and
the diagnostic_artifact_role::analysis_target of SARIF output from
creation of the sinks.  Calling it is done by the various creators
of the sinks.

gcc/ChangeLog:
	PR other/116792
	* diagnostic-format-html.cc (html_builder::m_title_element): New
	field.
	(html_builder::html_builder): Initialize it.  Don't add
	placeholder text.
	(html_builder::set_main_input_filename): New.
	(html_output_format::set_main_input_filename): New.
	(test_html_diagnostic_context::test_html_diagnostic_context): Call
	set_main_input_filename on the new sink.
	(seldtest::test_simple_log): Update expected <title> text.
	* diagnostic-format-json.cc (diagnostic_output_format_init_json):
	Return a reference to the new sink.
	(diagnostic_output_format_init_json_stderr): Likewise.
	(diagnostic_output_format_init_json_file): Likewise.
	* diagnostic-format-sarif.cc (sarif_builder::sarif_builder): Drop
	"main_input_filename_" param, and move adding an artifact for it
	with diagnostic_artifact_role::analysis_target to...
	(sarif_builder::set_main_input_filename): ...this new function.
	(sarif_output_format::set_main_input_filename): New.
	(sarif_output_format::sarif_output_format): Drop
	"main_input_filename_" param.
	(sarif_stream_output_format::sarif_stream_output_format):
	Likewise.
	(sarif_file_output_format::sarif_file_output_format): Likewise.
	(diagnostic_output_format_init_sarif): Return a reference to *FMT.
	(diagnostic_output_format_init_sarif_stderr): Return a refererence
	to the new sink.  Drop "main_input_filename_" param.
	(diagnostic_output_format_init_sarif_file): Likewise.
	(diagnostic_output_format_init_sarif_stream): Likewise.
	(make_sarif_sink): Drop "main_input_filename_" param.
	(selftest::test_sarif_diagnostic_context::test_sarif_diagnostic_context):
	Likewise.  Call set_main_input_filename on the new format.
	(selftest::test_sarif_diagnostic_context::buffered_output_format::buffered_output_format):
	Drop "main_input_filename_" param.
	(selftest::test_make_location_object): Likewise.
	* diagnostic-format-sarif.h
	(diagnostic_output_format_init_sarif_stderr): Return a refererence
	to the new sink.  Drop "main_input_filename_" param.
	(diagnostic_output_format_init_sarif_file): Likewise.
	(diagnostic_output_format_init_sarif_stream): Likewise.
	(make_sarif_sink): Drop "main_input_filename_" param.
	* diagnostic-format.h
	(diagnostic_output_format::set_main_input_filename): New vfunc.
	(diagnostic_output_format_init_json_stderr): Return a refererence
	to the new sink.
	(diagnostic_output_format_init_json_file): Likewise.
	* diagnostic.cc (diagnostic_output_format_init): Likewise.  Call
	set_main_input_filename on the new sink.
	* libgdiagnostics.cc (sarif_sink::sarif_sink): Update for above
	changes.
	* opts-diagnostic.cc (sarif_scheme_handler::make_sink): Likewise.
	(handle_OPT_fdiagnostics_add_output_): Likewise.
	(handle_OPT_fdiagnostics_set_output_): Likewise.

gcc/testsuite/ChangeLog:
	PR other/116792
	* gcc.dg/html-output/missing-semicolon.py: Update expected <title>
	text.  Drop out-of-date comment.

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