improved dynamic linking #383

Job	Run time
rustfmt_check (ubuntu-latest)	7s
rust_clippy_check_ubuntu	6m 28s
rustfmt_check (macos-latest)	11s
rustfmt_check (windows-latest)	21s
build_static_and_test_ubuntu_with_system_ffmpeg	1m 56s
build_dynamic_and_test_ubuntu	3m 44s
build_with_vcpkg_ffmpeg_windows (x86_64-pc-windows-msvc, x64-windows-static-md)	20m 29s
build_static_and_test_ubuntu	7m 3s
build_with_vcpkg_ffmpeg_windows (i686-pc-windows-msvc, x86-windows-static, -Ctarget-feature=+crt-...	20m 12s
build_with_vcpkg_ffmpeg_windows (i686-pc-windows-msvc, x86-windows, true)	18m 37s
build_dynamic_and_test_macos	3m 13s
build_with_vcpkg_ffmpeg_windows (x86_64-pc-windows-msvc, x64-windows, true)	21m 43s
build_with_vcpkg_ffmpeg_windows (x86_64-pc-windows-msvc, x64-windows-static, -Ctarget-feature=+cr...	22m 36s
build_dynamic_and_test_windows_pre	3m 32s
build_with_vcpkg_ffmpeg_windows (i686-pc-windows-msvc, x86-windows-static-md)	18m 17s
rust_clippy_check_windows	19m 59s
docs_rs_check	1m 13s
build_dynamic_and_test_windows	1m 17s
	2h 50m 58s

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