[CMake] BundleUtilities change to address change in behavior

[David Cole]

Clinton, (and anybody else reading who's interested / vested in the
BundleUtilities functionality),

Please review this change that I just pushed to 'next':
http://cmake.org/gitweb?p=cmake.git;a=commitdiff;h=c2895f48a4e79af49937b9e6a260076440b1a67a

As a result of fixing these two bugs...
http://public.kitware.com/Bug/view.php?id=9744
http://public.kitware.com/Bug/view.php?id=10417

...we introduced a backwards-incompatible change to 'fixup_bundle' in
CMake 2.8.3. This affected ParaView and possibly other apps that
passed in libs to fixup_bundle and used to depend on the function to
copy the plugins into the bundle...

We are going to keep the new code anyway (and just fix up ParaView
--it's already been done, in fact). This new commit that I pushed
today is for making it easy to diagnose when somebody is depending on
the old behavior by making it an error to try to fixup something that
is not already inside the bundle. (Arguably we should have had this
error checking all along because it is, in fact, an error to attempt
to fixup some library that is not inside the bundle...)

Let me know if you have thoughts positive or negative on this.

Thanks,
David Cole
Kitware, Inc.