Fix warning in stdio-common/tst-printf-round.c.

This patch fixes warnings of the form "tst-printf-round.c:202:17:
warning: passing argument 3 of 'test_hex_in_one_mode' discards 'const'
qualifier from pointer target type", by adding an extra const to that
argument (so that after array-to-pointer conversion it's const char
*const *).

Tested for x86_64.

	* stdio-common/tst-printf-round.c (test_hex_in_one_mode): Make
	third argument const.

ChangeLog

@@ -1,3 +1,8 @@
+2014-11-25  Joseph Myers  <joseph@codesourcery.com>
+
+	* stdio-common/tst-printf-round.c (test_hex_in_one_mode): Make
+	third argument const.
+
 2014-11-25  Paul Eggert  <eggert@cs.ucla.edu>
 
 	fnmatch: work around GCC compiler warning bug with uninit var

stdio-common/tst-printf-round.c

@@ -136,7 +136,7 @@ static const struct hex_test hex_tests[] =
   };
 
 static int
-test_hex_in_one_mode (double d, const char *fmt, const char *expected[4],
+test_hex_in_one_mode (double d, const char *fmt, const char *const expected[4],
 		      const char *mode_name)
 {
   char buf[100];