libutils/Unicode.cpp: Correct length computation and add checks for utf16->utf8 am: 53473c1607 am: 41e6690d0c am: 29ccafe5f0 am: fd7bd2dfef am: 498ffa62c5 am: 5e4ebd02d4 am: d837e74381 am: 6025b216e4 am: a73f7e5e81 am: 79a3c84cfe am: 17cd63d00a  -s ours am: b4c163b7b1
am: 127876e0c6

Change-Id: I657eac187582925d20b48828aed1c4d978493323