Tree-sitter: Emit empty_location relation to avoid scan

ruby/ql/lib/codeql/Locations.qll

@@ -64,5 +64,5 @@ class Location extends @location_default {
 
 /** An entity representing an empty location. */
 class EmptyLocation extends Location {
-  EmptyLocation() { this.hasLocationInfo("", 0, 0, 0, 0) }
+  EmptyLocation() { empty_location(this) }
 }

ruby/ql/lib/ruby.dbscheme

@@ -36,6 +36,12 @@ containerparent(
   unique int child: @container ref
 );
 
+/*- Empty location -*/
+
+empty_location(
+  int location: @location_default ref
+);
+
 /*- Source location prefix -*/
 
 /**