[CMake] can't remove RPATH from libtcl8.5.so (Linux) CMake Git version

[kent williams]

Answering my own question again -- this is a logged bug here:

http://public.kitware.com/Bug/view.php?id=9284

David Cole is of the opinion this error is useful in the context of
fixup_bundle.

Maybe so, but it's a right PITA.  If you're building the library
that's getting copied as part of fixup_bundle, and the permissions
don't allow RPATH_REMOVE to work, you're dead in the water until you
figure out how to add an install step to move the file and change the
permissions.

I'm dealing with it by adding a custom ExternalProject step to adjust
perms after the install.  Just getting that right was a whole other
story...