libutils/Unicode.cpp: Correct length computation and add checks for utf16->utf8 am: 3411dd4457 am: 01dbd1da64 am: 7c516d7080 am: 062c13e997  -s ours
am: 254b45e573

Change-Id: I8979227f652d831c15a40b26a14846789dcd5155