Fix clobber of the command line when using F-keys+LSS graphics

Fix clobber of the command line when using F-keys+LSS graphics

Fix a half-entered command line when getting clobbered when pressing
an F key that in turn invokes an LSS graphic.  This was used by
duplexing the command line buffer as LSS decompression space.

Allocate a separate buffer, but move the legacy graphic variables to
.bss2 to avoid overflow.

Reported-by: Михаил <from.miha@gmail.com>
Debugged-by: Sebastian Herbszt <herbszt@gmx.de>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>