C/C++ overlay: change discard predicate visibility

Author: IdrissRio

cpp/ql/lib/semmle/code/cpp/internal/Overlay.qll

@@ -21,7 +21,7 @@ private string getLocationFilePath(@location_default loc) {
  * Gets the file path for an element with a single location.
  */
 overlay[local]
-private string getSingleLocationFilePath(@element e) {
+string getSingleLocationFilePath(@element e) {
   exists(@location_default loc |
     var_decls(e, _, _, _, loc)
     or
@@ -43,7 +43,7 @@ private string getSingleLocationFilePath(@element e) {
  * Gets the file path for an element with potentially multiple locations.
  */
 overlay[local]
-private string getMultiLocationFilePath(@element e) {
+string getMultiLocationFilePath(@element e) {
   exists(@location_default loc |
     exists(@var_decl vd | var_decls(vd, e, _, _, loc))
     or