diagnostics: eliminate diagnostic_context::m_make_json_for_path

diagnostics: eliminate diagnostic_context::m_make_json_for_path

Now that the path-handling code for json_output_format no longer
needs "tree", and thus can be in OBJS-libcommon we can move it
from tree-diagnostic-path.cc to diagnostic-format-json.cc where it
should have been all along.

No functional change intended.

gcc/ChangeLog:
	* diagnostic-format-json.cc: Include "diagnostic-path.h" and
	"logical-location.h".
	(make_json_for_path): Move tree-diagnostic-path.cc's
	default_tree_make_json_for_path here, renaming it and making it
	static.
	(json_output_format::on_end_diagnostic): Replace call of
	m_context's m_make_json_for_path callback with a direct call to
	make_json_for_path.
	* diagnostic.h (diagnostic_context::m_make_json_for_path): Drop
	field.
	* tree-diagnostic-path.cc: Drop include of "json.h".
	(default_tree_make_json_for_path): Rename to make_json_for_path
	and move to diagnostic-format-json.cc.
	* tree-diagnostic.cc (tree_diagnostics_defaults): Drop
	initialization of m_make_json_for_path.
	* tree-diagnostic.h (default_tree_make_json_for): Delete decl.

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