[HD04] Make the locale mandatory.

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

...android/inputmethod/latin/ExpandableBinaryDictionary.java

...m/android/inputmethod/latin/makedict/Ver4DictEncoder.java

...ve/jni/com_android_inputmethod_latin_BinaryDictionary.cpp

...rc/suggest/policyimpl/dictionary/header/header_policy.cpp

.../src/suggest/policyimpl/dictionary/header/header_policy.h

.../policyimpl/dictionary/header/header_read_write_utils.cpp

...st/policyimpl/dictionary/header/header_read_write_utils.h

...t/policyimpl/dictionary/utils/dict_file_writing_utils.cpp

...est/policyimpl/dictionary/utils/dict_file_writing_utils.h

native/jni/src/utils/char_utils.cpp

native/jni/src/utils/char_utils.h

...roid/inputmethod/latin/BinaryDictionaryDecayingTests.java

.../com/android/inputmethod/latin/BinaryDictionaryTests.java