ENH: Implement feature request from issue 7885. Allow setting environment variables on a per-test basis for ctest using set_test_properties ENVIRONMENT.

BUG:  Revert 1.138.

When we install a target on Mac, we generate a call to install_name_tool to fix
install_name entries in the target for shared libraries it links.  This change
makes the step ignore entries for imported targets since their install_name
will not change and cmTarget cannot produce a mapping for them.  This fixes the
error

  GetLibraryNamesInternal called on imported target: kdelibs

seen by kde folks.