TAKE - Trade in panic() for BUG() in debug kernel

[Eric Sandeen <sandeen@xxxxxxx>]

There was a spot in here that would panic() the system,
but that left the system useless for debugging; BUG() will
let us get into kdb and see what's going on.

Date:  Tue May 21 15:32:45 PDT 2002
Workarea:  
stout.americas.sgi.com:/localhome/src/sandeen/2.4.x-xfs/workarea-testing

The following file(s) were checked into:
  bonnie.engr.sgi.com:/isms/slinx/2.4.x-xfs


Modid:  2.4.x-xfs:slinx:119800a
linux/fs/xfs/xfs_da_btree.c - 1.126
        - Don't panic on the xfs_buftrace error, BUG() so we can still use kdb