OSV-2020-1813 Heap-buffer-overflow in flb_msgpack_to_gelf

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=25780 Crash type: Heap-buffer-overflow READ 4 Crash state: flbmsgpacktogelf flbmsgpackrawtogelf msgpacktogelffuzzer.c...