Review Request 114336: Install all includes in a KF5 dir

[Stephen Kelly]

Aurélien Gâteau wrote:

> target_include_directories(${library} INTERFACE
> "$<INSTALL_INTERFACE:
> ${CMAKE_INSTALL_PREFIX}/${${library}_INCLUDE_INSTALL_DIR}>"
> )

Note that this makes the resulting package non-relocatable. If using CMake 
3.0.0, you can specify a relative path here. With 2.8.12, you should use 
$<INSTALL_PREFIX> instead of ${CMAKE_INSTALL_PREFIX} so that the relative 
path stays relative.

Thanks,

Steve.