support DB_PROGRAM to be absolute, relative or in PATH #14173

Job	Run time
htmldocs	20m 33s
rip-and-test-clang	14m 42s
cppcheck	6m 5s
rip-and-test	14m 10s
rip-rtai	8m 51s
package-indep (debian:sid)	29m 24s
package-indep (debian:trixie)	38m 13s
package-indep (debian:bookworm)	38m 19s
package-arch (ubuntu-24.04-arm, debian:sid)	16m 35s
package-arch (ubuntu-24.04, debian:bookworm)	18m 26s
package-arch (ubuntu-24.04-arm, debian:bookworm)	14m 58s
package-arch (ubuntu-24.04, debian:trixie)	18m 44s
package-arch (ubuntu-24.04, debian:sid)	19m 11s
package-arch (ubuntu-24.04-arm, debian:trixie)	16m 35s
Release packages	0s
	4h 34m 46s

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