change invalid characters when get user data dir on Windows & Unix

Can't create user data folder when project name has ``\ / : * ? " < > |`` characters on OS_Windows & OS_Unix.
So, change it to ``-`` to be able to make folder.

fixes #4928 and it's altanative to #4986.

(cherry picked from commit 9073dc9963)

drivers/unix/os_unix.cpp

@@ -456,7 +456,7 @@ int OS_Unix::get_processor_count() const {
 
 String OS_Unix::get_data_dir() const {
 
-	String an = Globals::get_singleton()->get("application/name");
+	String an = get_safe_application_name();
 	if (an!="") {