nettle-benchmark: Use PRINTF_STYLE attribute.

ChangeLog

 2012-09-10  Niels Möller  <nisse@lysator.liu.se>
 
 	From Tim Rühsen:
+	* examples/nettle-benchmark.c (die): Use PRINTF_STYLE attribute.
 	* pgp-encode.c (pgp_put_rsa_sha1_signature): Deleted unused variable.
 	* rsa2openpgp.c (rsa_keypair_to_openpgp): Likewise.
 	* examples/base16enc.c (main): Deleted useless allocations.

examples/nettle-benchmark.c

@@ -96,7 +96,7 @@ static double frequency = 0.0;
 #define BENCH_ITERATIONS 10
 #endif
 
-static void NORETURN
+static void NORETURN PRINTF_STYLE(1,2)
 die(const char *format, ...)
 {
   va_list args;