Attn: maintainers of rxvt-derived ports: small crash fixed

[Marcin Cieslak]

Hello,

There are some rxvt-derived ports in the tree and I have fixed
a small possibility to crash the emulator when pasting some
text from not-fully-ICCCM compliant client.

Here's patch for x11/rxvt:
http://www.freebsd.org/cgi/query-pr.cgi?pr=156542

for x11/rxvt-devel:
http://www.freebsd.org/cgi/query-pr.cgi?pr=156544

for x11/rxvt-unicode:
http://www.freebsd.org/cgi/query-pr.cgi?pr=156509

The patch is trivial and changes ca. 4 lines of code,
I just don't have time to fix all the rxvt derivatives
right there, notify upstream etc. 

I would also welcome feedback from X11 experts
whether this patch is a RightThing(tm) to do.

//Marcin