lib/vsprintf.c: remove %Z support

Now that %z is standartised in C99 there is no reason to support %Z.
Unlike %L it doesn't even make format strings smaller.

Use BUILD_BUG_ON in a couple ATM drivers.

In case anyone didn't notice lib/vsprintf.o is about half of SLUB which
is in my opinion is quite an achievement.  Hopefully this patch inspires
someone else to trim vsprintf.c more.

Link: http://lkml.kernel.org/r/20170103230126.GA30170@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

net/atm/mpc.c

@@ -451,7 +451,7 @@ static void lane2_assoc_ind(struct net_device *dev, const u8 *mac_addr,
 			return;
 	}
 	if (end_of_tlvs - tlvs != 0)
-		pr_info("(%s) ignoring %Zd bytes of trailing TLV garbage\n",
+		pr_info("(%s) ignoring %zd bytes of trailing TLV garbage\n",
 			dev->name, end_of_tlvs - tlvs);
 }