fixes (again) installation with ocamlfind

commit 0eba52e72bde07b4cd01ffa9dd0a22d00e09a156 fixed the findlib installation of bytecode version of the GUI, but some files (*.o to be precise) were still missing. This patch installs the same set of files in install-findlib and install-(opt,byte) for ```VIEWER``` and ```DGRAPH```