github: Install libltdl-dev in the linux-cross-windows build job #1503

Job	Run time
prepare	3s
msys2 (mingw64)	2h 18m 50s
linux	3h 8m 38s
macos	2h 22m 4s
msys2 (clang64)	1h 49m 26s
linux-asserts	0s
linux-test-cross-build-ffmpeg	0s
linux-cross-aarch64	3h 16m 33s
linux-cross-windows (i686, ucrt)	3h 12m 44s
linux-cross-windows (x86_64, ucrt)	3h 12m 48s
linux-cross-windows (armv7, ucrt)	3h 7m 53s
linux-cross-windows (aarch64, ucrt)	3h 10m 47s
test-compiler-rt	0s
test-ffmpeg	0s
test-libcxx	0s
test-openmp	0s
test-toolchain (x86_64)	2m 12s
test-toolchain (i686)	2m 41s
upload-nightly	0s
	1d 1h 44m 39s

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