x86: Clean up and extend do_int3()

x86: Clean up and extend do_int3()

Since there is a possibility of !KPROBES int3 listeners
(such as kgdb) and since DIE_TRAP is currently not being
used by anybody, notify all listeners with DIE_INT3.

Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20111025142159.GB21225@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>