gEDA-dev: more polygon failures

[DJ Delorie]

pcb is now crashing fairly regularly :-P

I took out all the negative-keepout lines and this goes away, but I
still have the "blinking polygon" bug.  I"m hoping one of Ben's
patches fixes it.

Program received signal SIGSEGV, Segmentation fault.
0x0809f112 in M_POLYAREA_intersect (e=0xbfdebd80, afst=0x99e0f10, bfst=0x9b258c8, add=1)
    at polygon1.c:848
848               if (a->contours->xmax >= b->contours->xmin &&

#0  0x0809f112 in M_POLYAREA_intersect (e=0xbfdebd80, afst=0x99e0f10, bfst=0x9b258c8, 
    add=1) at polygon1.c:848
#1  0x080a0566 in poly_AndSubtract_free (ai=0x99e0f10, bi=0x9b258c8, aandb=0xbfdebee8, 
    aminusb=0xbfdebee4) at polygon1.c:1811
#2  0x0809bb21 in r_NoHolesPolygonDicer (p=0x9a69a68, 
    emit=0x8079fe0 <DrawPolygonLowLevel>) at polygon.c:1300
#3  0x0809bb5a in r_NoHolesPolygonDicer (p=0x9a14670, 
    emit=0x8079fe0 <DrawPolygonLowLevel>) at polygon.c:1322
#4  0x0809bccc in NoHolesPolygonDicer (p=0x94e9c78, 
    emit=0x8079fe0 <DrawPolygonLowLevel>, clip=0xbfdec2c8) at polygon.c:1358
#5  0x0807a210 in poly_callback (b=0x94e9c78, cl=0xbfdec0f4) at draw.c:2012
#6  0x080a9ae4 in __r_search (node=0x94e9e98, query=0xbfdec2c8, arg=0xbfdec090)
    at rtree.c:540
#7  0x080a9bcc in r_search (rtree=0x94e9e88, query=0x0, check_region=0, 
    found_rectangle=0x807a190 <poly_callback>, cl=0xbfdec0f4) at rtree.c:626
#8  0x0807a5a9 in DrawLayerGroup (group=<value optimized out>, screen=0xbfdec2c8)
    at draw.c:854
#9  0x0807bda3 in hid_expose_callback (hid=0x80ef460, region=0xbfdec2c8, item=0x0)
    at draw.c:443
#10 0x080c1ad5 in idle_proc (dummy=0x0) at hid/lesstif/main.c:2452
#11 0x00659003 in XtNoticeSignal () from /usr/lib/libXt.so.6
#12 0x0065aed4 in XtAppNextEvent () from /usr/lib/libXt.so.6
#13 0x0064dce4 in XtAppMainLoop () from /usr/lib/libXt.so.6
#14 0x080bf164 in lesstif_do_export (options=0x0) at hid/lesstif/main.c:1892
#15 0x0808cff0 in main (argc=162754, argv=0xdcb4) at main.c:1005

[ gdb ] p b->contours
$2 = (PLINE *) 0x0

[ gdb ] p *b
$3 = {f = 0x9b258c8, b = 0x9b258c8, contours = 0x0}