S390: Fix build error in iconvdata/bug-iconv11.c.

This fixes the following build error on S390 31bit while building the test
iconvdata/bug-iconv11.c with gcc 5.3:
bug-iconv11.c: In function ‘test_ibm93x’:
bug-iconv11.c:59:11: error: format ‘%td’ expects argument of type ‘ptrdiff_t’, but argument 2 has type ‘size_t {aka long unsigned int}’ [-Werror=format=]
   printf ("  ==> %td: %s\n"
           ^
cc1: all warnings being treated as errors

This patch uses %zu format specifier for argument size_t ret instead of %td.

ChangeLog:

	* iconvdata/bug-iconv11.c (test_ibm93x):
	Use %zu printf format specifier for size_t argument.

ChangeLog

@@ -1,3 +1,8 @@
+2016-01-19  Stefan Liebler  <stli@linux.vnet.ibm.com>
+
+	* iconvdata/bug-iconv11.c (test_ibm93x):
+	Use %zu printf format specifier for size_t argument.
+
 2016-01-19  Joseph Myers  <joseph@codesourcery.com>
 
 	* math/gen-libm-test.pl (parse_ulps): Do not reduce

iconvdata/bug-iconv11.c

@@ -56,7 +56,7 @@ test_ibm93x (const char *from_set, const char *input, size_t inbytesleft)
 
   errno = 0;
   size_t ret = iconv (cd, &inbuf, &inbytesleft, &outbuf, &outbytesleft);
-  printf ("  ==> %td: %s\n"
+  printf ("  ==> %zu: %s\n"
           "  inbuf%+td, inbytesleft=%zu, outbuf%+td, outbytesleft=%zu\n",
           ret, strerror (errno),
           inbuf - input, inbytesleft, outbuf - output, outbytesleft);