OSV-2018-174 Heap-buffer-overflow in BEInt<unsigned char, 1>::operator unsigned char

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=11245 Crash type: Heap-buffer-overflow READ 1 Crash state: BEInt::operator unsigned char OT::KernSubTableFormat3::getkerning hbkernmachinet::kern...