[CMake] install(EXPORT ..) and multiple projects

[Clinton Stimpson]

I've got two projects with one depending on the other.  I include the 
one project as a subdirectory and build it along with my project.  Its 
similar to how ParaView includes VTK.
I'm trying to use the install(EXPORT ...) to export my project from an 
installation tree, but I can't figure out how to make it work.
The export(TARGETS ...) works fine for exporting from the build, except 
I have to include libraries from the other project.

install(EXPORT ..) gives me an error
CMake Error: INSTALL(EXPORT "Foo" ...) includes target "Bar" which 
requires target "Baz" that is not in the export set.

Baz is from the other project I include as a subproject.  It seems "Foo" 
is supposed to be a name specific to my project.
So I can't just add my project specific name for the export set into the 
other project's CMakeLists.txt file.

So how do I export targets from an installation tree that contains 
multiple projects?

Clint