[CMake] INSTALL(EXPORT) does not honor LINK_INTERFACE_LIBRARIES?

[Rolf Eike Beer]

> You still need to install that lib even if it is not used by 3rd party
> application, it is used inernally by your own application.
>
> INSTALL(TARGETS publiclib privatelib...)

The private libraries are of course installed. If I link against that
installed public library "by hand" everything works fine.

And of course that INSTALL instruction is not working because privatelib
is in a different directory.

Eike