Add bound checks to utf16_to_utf8

Bug: 29250543
Change-Id: I518e7b2fe10aaa3f1c1987586a09b1110aff7e1a
(cherry picked from commit 7e93b2ddcb49b5365fbe1dab134ffb38e6f1c719)

status_t Parcel::writeByteVector(const std::vector<int8_t>& val) {
 return writeByteVectorInternal(this, val);
}

status_t Parcel::writeByteVector(const std::vector<int8_t>& val) {
 return writeByteVectorInternal(this, val);
}
