virtualbox: clipboard sharing

[Andriy Gapon]

It seems that currently virtualbox port doesn't build/install VBoxSharedClipboard.so.

It seems that fixing this should be as simple as removing wrapping if1of check in
src/VBox/HostServices/Makefile.kmk (or adding freebsd to the list).
The same operation is then needed in
src/VBox/HostServices/SharedClipboard/Makefile.kmk where VBoxSharedClipboard_LIBS
is set, so that VBoxSharedClipboard.so is linked with libXt and libX11.


-- 
Andriy Gapon