add demux4 component #784

Job	Run time
rip-and-test	25m 28s
package-indep (debian:buster)	39m 55s
package-arch (debian:buster)	26m 56s
package-indep (debian:bullseye)	38m 9s
package-arch (debian:bullseye)	27m 53s
rip-and-test-clang	25m 32s
package-indep (debian:bookworm)	29m 37s
package-arch (debian:bookworm)	29m 2s
htmldocs	21m 53s
package-indep (debian:sid)	29m 43s
package-arch (debian:sid)	30m 57s
	5h 25m 5s

Provide feedback