Fix ArrayList to List implicit conversion

Author: facchinm

Diff for: arduino-core/src/processing/app/BaseNoGui.java

@@ -245,7 +245,7 @@ static public String getHardwarePath() {
     return getHardwareFolder().getAbsolutePath();
   }
 
-  static public List<File> getLibrariesPath() {
+  static public ArrayList<File> getLibrariesPath() {
     return librariesFolders;
   }