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: I99a21536238f7ac5b0e0778d7608fc6ef8f5dea9