When using `dpkg-shlibdeps` to automatically determine package
dependencies it considers the RUNPATH/RPATH of executables in order to
find all required shared libraries of such executables.
If the RUNPATH/RPATH contains a verbatim `$ORIGIN` (respective
`${ORIGIN}`), it will now be substituted by the packaging-paths of other
components that are marked as dependency and those paths will then be
used as additional search directories for `dpkg-shlibdeps`.
Associated tests were added as well.
Fixes: #21838
The new CPack variable `CPACK_DEBIAN_PACKAGE_SHLIBDEPS_PRIVATE_DIRS`
can be set to a list of directories. If `CPACK_DEBIAN_PACKAGE_SHLIBDEPS`
or `CPACK_DEBIAN_<component>_PACKAGE_SHLIBDEPS` are set to `ON` these
directories will be searched by `dpkg-shlibdeps` in order to find
private shared library dependencies of the libraries/executables that
shall be packed.
