RadeonValidateFPModes() has a bug where it could try to dereference
a NULL pointer in some cases when linking in modes. This fixes it.

Index: xc/programs/Xserver/hw/xfree86/drivers/ati/radeon_driver.c
===================================================================
--- xc.orig/programs/Xserver/hw/xfree86/drivers/ati/radeon_driver.c     2004-12-05 20:22:11.921507352 +1100
+++ xc/programs/Xserver/hw/xfree86/drivers/ati/radeon_driver.c  2004-12-05 20:22:15.015037064 +1100
@@ -3283,8 +3283,9 @@
               new->next       = NULL;
               new->prev       = last;

-               last->next = new;
+               if (last) last->next = new;
               last = new;
+               if (!first) first = new;
           }
       }
    }