r21690 - gnucash/trunk/src/gnome - Avoid risk on a rare crash after r21680.

[Geert Janssens]

Author: gjanssens
Date: 2011-12-08 12:11:52 -0500 (Thu, 08 Dec 2011)
New Revision: 21690
Trac: http://svn.gnucash.org/trac/changeset/21690

Modified:
   gnucash/trunk/src/gnome/gnc-plugin-page-register.c
Log:
Avoid risk on a rare crash after r21680.
Some data files may only have filter[0] in which case filter[1] is NULL
and filter[2] invalid. A rare situation, but I have one test data file
consistently crashing on this.
I also took the opportunity to convert from strcmp to g_strcmp0.