Reference OBJECT libraries for inclusion in targets that have no other
sources to verify that the linker language propagates correctly from the
object libraries.  Test with a STATIC library, a SHARED library, and an
EXECUTABLE target.  Use the static and shared libraries each in
executables that end up using the object library symbols.

In VS 6, 7, and 7.1 add a dummy object file to convince the IDE to build
the targets without sources.  In Xcode add a dummy source file to
convince it to build targets without sources.