MFC 1.8:

MFC 1.8:
o  As mentioned in the previous commit: make the KVM error buffer
   static.
o  Register a function with atexit(3) to close the KVM object if
   we have one open.
o  Show the unread portion of the kernel's message buffer before
   presenting the prompt. It's bound to provide some useful info.
o  Don't call kgdb_target() twice. It results in having all threads
   listed twice.

Approved by: re (hrs)