PDP11: EXAMINE of register arrays may display incorrect data

[shattered]

Transcript (start the simulator with no configuration file):

sim> ex rx sbuf[0/4]
SBUF[0]:        000
SBUF[1]-SBUF[3]: same as above
sim> dep rx sbuf[2] 1
sim> ex rx sbuf[0/4]
SBUF[0]:        000
SBUF[1]:        001
SBUF[2]:        001
SBUF[3]:        000
sim> ex sbuf[1]
SBUF[1]:        000
sim> ex sbuf[2]
SBUF[2]:        001

Seems to be an off-by-one somewhere, but I don't quite understand the code to find it.

[markpizz]

If or when #502 is merged, the reported problem will be fixed.