EPL + openSAFETY: Better handling of guint in EPL

EPL + openSAFETY: Better handling of guint in EPL

 This is a permanent solution for bug #9786. guint overflows
 are now prevented, and the remaining length is queried from
 tvb and taken into consideration.

 As a side-effect, the fix brought up two bugs in the openSAFETY
 dissector, which where fixed as well.

 Upd: Remove stdio.h and fix one encoding error found by
 fix-encoding-args.pl

Change-Id: Ic2d478a8ea15b0bcfd2536a074c217daf610fe08
Reviewed-on: https://code.wireshark.org/review/291
Reviewed-by: Roland Knall <rknall@gmail.com>
Reviewed-by: Evan Huus <eapache@gmail.com>