Revert "Export the INCLUDES DESTINATION without appending to the target."

This reverts commit aa4b57072969f899a65dd52602a77328906dc74f.
Revert "Add a convenient way to add the includes install dir to the INTERFACE."

This reverts commit 537ab88be837f33903663afcbe9da33f13c727a1.
Merge topic 'install-interface-includes' into next

94316ed Revert "Add a convenient way to add the includes install dir to the INTERFACE."
45fbf68 Revert "Export the INCLUDES DESTINATION without appending to the target."