OSV-2020-82 Heap-buffer-overflow in template_image_compose_opt

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=20332 Crash type: Heap-buffer-overflow WRITE 1 Crash state: templateimagecomposeopt jbig2imagecomposeoptREPLACE jbig2imagecompose...