Platform-specific dependencies

[arikrupnik]

LTCsync has dependencies on three binary executables, ffprobe(1), ffmpeg(1) and ltcdump(1). Binary distribution must include platform specific copies of these binaries. There is no need to compile (cross-compile) binaries on every build. In fact, the ffmpeg project makes static binaries available at https://www.ffmpeg.org/download.html. For ltcdump, we may need to compile binaries ourselves for each platform we support. Since a full build must produce binaries for all platforms, and since the upstream changes infrequently, we may want to keep static binaries for ltcdump binaries instead of cross-compiling them on every build.

[arikrupnik]

Many thanks to Robin Gareus for making static binaries available for the current version of ltcdump: x42/ltc-tools#13.