cmTarget: Remove dead code.

Whitelisting of properties already ensures that the LOCATION
property will not be read from an INTERFACE_LIBRARY.
cmTarget: Enable convenient include dir handling for INTERFACE_LIBRARY.

Make the CMAKE_INCLUDE_CURRENT_DIR_IN_INTERFACE variable affect
INTERFACE_LIBRARY targets.
Merge topic 'minor-cleanups' into next

1cd0a8f cmTarget: Enable convenient include dir handling for INTERFACE_LIBRARY.
867058c cmTarget: Remove dead code.