The idea of the patch is to let the install generator define
CPACK_ABSOLUTE_INSTALL_FILES then when CMake is installing
project he will concatenate the list of files and give
it to specific CPack Generator by defining CPACK_ABSOLUTE_INSTALL_FILES
to be the list of ALL files that were installed using absolute destination.
An example of use has been applied to RPM generator which now
tries to automatically build a relocatable package.
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