emulators/virtualbox-ose: Add VBoxSharedClipboard.so to non X11 builds

This library is built when X11 is disabled too, since the functionality
can also be used by remote protocols.

PR: 261729
MFH: 2022Q3
(cherry picked from commit 5f02996b2b84deafaca8c5d6c3a2486695cb67ef)