libutils/Unicode.cpp: Correct length computation and add checks for utf16->utf8 am: 3411dd4457 am: 01dbd1da64 am: 7c516d7080 am: 062c13e997  -s ours am: 254b45e573 am: cf76ba7f7b
am: 7ac4fb8375

Change-Id: I1ca174d7b87117e41df8eaf811ac1060c2683843