Double free

GNU LibreDWG 0.12.3.4163 through 0.12.3.4191 has a double-free in bitchainfree called from dwgencodeMTEXT and dwgencodeaddobject...

OSV-2021-495 Heap-double-free in bit_chain_free

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=31724 Crash type: Heap-double-free Crash state: bitchainfree dwgencodeMTEXT dwgencodeaddobject...