fs/signalfd: fix build error for BUS_MCEERR_AR

Fix build error in fs/signalfd.c by using same method that is used in
kernel/signal.c: separate blocks for different signal si_code values.

./fs/signalfd.c: error: 'BUS_MCEERR_AR' undeclared (first use in this function)
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

fs/signalfd.c

@@ -123,8 +123,17 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
 		 * so check explicitly for the right codes here.
 		 */
 		if (kinfo->si_signo == SIGBUS &&
-		    (kinfo->si_code == BUS_MCEERR_AR ||
-		     kinfo->si_code == BUS_MCEERR_AO))
+		     kinfo->si_code == BUS_MCEERR_AO)
+			err |= __put_user((short) kinfo->si_addr_lsb,
+					  &uinfo->ssi_addr_lsb);
+#endif
+#ifdef BUS_MCEERR_AR
+		/*
+		 * Other callers might not initialize the si_lsb field,
+		 * so check explicitly for the right codes here.
+		 */
+		if (kinfo->si_signo == SIGBUS &&
+		    kinfo->si_code == BUS_MCEERR_AR)
 			err |= __put_user((short) kinfo->si_addr_lsb,
 					  &uinfo->ssi_addr_lsb);
 #endif