[Locale] fixed build-data exit code in case of an error

When passing a message to the exit() function, PHP returns 0 instead of
an error code.

src/Symfony/Component/Locale/Resources/data/build-data.php

@@ -11,7 +11,9 @@
 
 function bailout($message)
 {
-    exit($message."\n");
+    echo $message."\n";
+
+    exit(1);
 }
 
 function check_dir($source)