powerpc: kill the obsolete code under is_global_init()

The code under "if (is_global_init())" is bogus, and is_global_init()
itself is not right in mt case.

Contrary to what the comment says, nowadays force_sig_info() does kill
init even if the handler is SIG_DFL. Note that force_sig_info() clears
SIGNAL_UNKILLABLE exactly for this case.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/traps.c

@@ -198,28 +198,6 @@ void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
 	info.si_code = code;
 	info.si_addr = (void __user *) addr;
 	force_sig_info(signr, &info, current);
-
-	/*
-	 * Init gets no signals that it doesn't have a handler for.
-	 * That's all very well, but if it has caused a synchronous
-	 * exception and we ignore the resulting signal, it will just
-	 * generate the same exception over and over again and we get
-	 * nowhere.  Better to kill it and let the kernel panic.
-	 */
-	if (is_global_init(current)) {
-		__sighandler_t handler;
-
-		spin_lock_irq(&current->sighand->siglock);
-		handler = current->sighand->action[signr-1].sa.sa_handler;
-		spin_unlock_irq(&current->sighand->siglock);
-		if (handler == SIG_DFL) {
-			/* init has generated a synchronous exception
-			   and it doesn't have a handler for the signal */
-			printk(KERN_CRIT "init has generated signal %d "
-			       "but has no handler for it\n", signr);
-			do_exit(signr);
-		}
-	}
 }
 
 #ifdef CONFIG_PPC64