tests: test-argv-iter.c: avoid declaration-after-stmt

* gl/tests/test-argv-iter.c: Move declaration "up", so as not
to ruffle feathers of crufty compilers.  We accommodate such
compilers here solely because this module may migrate to gnulib.
Tiny patch by Matthew Woehlke.

gl/tests/test-argv-iter.c

@@ -72,6 +72,7 @@ main ()
         {
           FILE *fp;
           struct argv_iterator *ai;
+          size_t n_found = 0;
           if (use_stream)
             {
               /* Generate an identical list to be read via FP.  */
@@ -85,7 +86,6 @@ main ()
             }
           ASSERT (ai);
 
-          size_t n_found = 0;
           while (1)
             {
               enum argv_iter_err ai_err;