Segmentation fault in xclip_handle_SelectionNotify

I resoloved this SIGSEGV with the attached patch.

(gdb) bt
#0 0x40268d89 in free () from /lib/tls/libc.so.6
#1 0x401658df in XFree () from /usr/X11R6/lib/libX11.so.6
#2 0x08056e2a in xclip_handle_SelectionNotify
(event=0x40328e80)
at xclip.c:506
#3 0x08051b3f in xwin_process_events () at xwin.c:1749
#4 0x08051c18 in ui_select (rdp_socket=7) at xwin.c:1785
#5 0x08058bfe in tcp_recv (s=0x80b0680, length=4) at
tcp.c:110
#6 0x0805916f in iso_recv_msg (code=0x3e3 <Address
0x3e3 out of bounds>,
rdpver=0xbfffefbf "懣植) at iso.c:81
#7 0x080592ef in iso_recv (rdpver=0xbfffefbf "懣植) at
iso.c:156
#8 0x08059c6d in mcs_recv (channel=0xbfffef9a,
rdpver=0xbfffefbf "懣植)
at mcs.c:349
#9 0x0805b23b in sec_recv (rdpver=0xbfffefbf "懣植) at
secure.c:827
#10 0x0805be0b in rdp_recv (type=0xbfffefdb "") at rdp.c:86
#11 0x0805dab8 in rdp_loop (deactivated=0xbffff054,
ext_disc_reason=0xbffff058)
at rdp.c:1370
#12 0x0805da8c in rdp_main_loop (deactivated=0xbffff054,
ext_disc_reason=0xbffff058) at rdp.c:1355
#13 0x0804cc88 in main (argc=1, argv=0xbffff274) at
rdesktop.c:834
(gdb)