[CMake] Update/Set _expectedTargets inside exports-release.cmake.

[Stephen Kelly]

Rashad Kanavath wrote:

> I am having this when I build packages for debian where I split components
> into separate packages project1-core, project1-gui etc..

I think you need to patch the buildsystems of the software you are packaging 
so that they support that kind of split by exporting to a different export-
set per split component.

ie:

install(TARGETS project1-core EXPORT CoreExports ...)
install(TARGETS project1-gui EXPORT GuiExports ...)
install(TARGETS project1-network EXPORT NetworkExports ...)

and put conditional includes for the resulting files in the 
Project1Config.cmake file.

Thanks,

Steve.