Disallow negative coordinates and sizes in the syscons CONS_SCRSHOT ioctl.
Disallow negative coordinates and sizes in the syscons CONS_SCRSHOT
ioctl.

Reported by:	Christer Oberg <christer.oberg@deprotect.com>

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase