catapult,irda: Fix ASAN crashes due to buffer underrun

The catapult dissector tripped on this random file I had. A quick look
at other dissectors which use a construct like "-1] *= '*\\[rn]" showed
packet-irda too, so fix that as well.

Change-Id: I4b5fadcacd0b09d0fb29bdefc3dd1f28aef9b593
Reviewed-on: https://code.wireshark.org/review/2802
Reviewed-by: Evan Huus <eapache@gmail.com>
Reviewed-by: Michael Mann <mmann78@netscape.net>