multimedia/Bento4: update to v1.6.0-640

Major changes:

• Add missed AP4_DEFINE_DYNAMIC_CAST_ANCHOR()
• Add multi-segment option for mp4encrypt
• Fix copy of file name may not be NUL-terminated
• Fix subtitles with mp4-dash
• Fix incorrect boundary check in AP4_HdlrAtom::WriteFields resulting in global-buffer-overflow
• Bug stack memory exhaustion and program crash caused by an infinite recursion
• Add Dolby Digital Plus Atmos signaling for HLS
• add --allow-cache option
• Fix a gobal-buffer-overflow in Ap4ByteStream.cpp
• Fix mp4encrypt scans and overwrites potentially non NUL-terminated file name
• avcinfo, hevcinfo: check buffer size #656
• Fix duration of muxed mp4 video is too long
• Add DDP including JOC signaling for DASH
• Add AC4 signaling including IMS to DASH
• Add AC4 with immersive stereo (IMS) signaling for DASH
• Fix heap-Buffer-Overflow with ASAN in mp42hls

Full changelog: https://github.com/axiomatic-systems/Bento4/compare/v1.6.0-639...v1.6.0-640