cmake install DESTDIR issues on OSX

[Benjamin Reed]

It looks like there's some kind of post-processing going on during a
make install, but if using DESTDIR, you get errors like this:

-- Installing /opt/roots/kdelibs/opt/kde4/bin/dcopserver
install_name_tool: can't open file: /opt/kde4/bin/dcopserver (No such
file or directory)
-- Installing /opt/roots/kdelibs/opt/kde4/lib/libDCOP.dylib.5.0.0
-- Installing /opt/roots/kdelibs/opt/kde4/include/dcopclient.h
-- Installing /opt/roots/kdelibs/opt/kde4/include/dcopobject.h
-- Installing /opt/roots/kdelibs/opt/kde4/include/dcopstub.h
-- Installing /opt/roots/kdelibs/opt/kde4/include/dcopref.h
-- Installing /opt/roots/kdelibs/opt/kde4/include/dcoptypes.h
-- Installing /opt/roots/kdelibs/opt/kde4/include/kdatastream.h
-- Installing /opt/roots/kdelibs/opt/kde4/lib/libkdeinit_dcopserver.dylib
install_name_tool: can't open file:
/opt/kde4/lib/libkdeinit_dcopserver.dylib (No such file or directory)