uml: dump core on panic

Dump core after a panic.  This will provide better debugging information than
is currently available.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/um/kernel/um_arch.c

@@ -474,7 +474,7 @@ static int panic_exit(struct notifier_block *self, unsigned long unused1,
 	show_regs(&(current->thread.regs));
 	bust_spinlocks(0);
 	uml_exitcode = 1;
-	machine_halt();
+	os_dump_core();
 	return 0;
 }