Use Locale.ROOT for locale neutral operations

...c/com/android/inputmethod/dictionarypack/LocaleUtils.java

java/src/com/android/inputmethod/keyboard/Key.java

java/src/com/android/inputmethod/keyboard/KeyboardId.java

java/src/com/android/inputmethod/latin/LocaleUtils.java

java/src/com/android/inputmethod/latin/Suggest.java

...oid/inputmethod/keyboard/internal/KeySpecParserTests.java