m4: fix false negative working iconv test

Part of the test is leaking memory, which can trip the leak sanitizer.

(This should be fixed in gettext. In the mean time, it will need to be
 applied manually at every gettext update.)

m4/iconv.m4

@@ -165,6 +165,7 @@ AC_DEFUN([AM_ICONV_LINK],
       }
   }
 #endif
+#if 0 /* This test leaks and we do not care about HP-UX. */
   /* Test against HP-UX 11.11 bug: No converter from EUC-JP to UTF-8 is
      provided.  */
   if (/* Try standardized names.  */
@@ -176,6 +177,7 @@ AC_DEFUN([AM_ICONV_LINK],
       /* Try HP-UX names.  */
       && iconv_open ("utf8", "eucJP") == (iconv_t)(-1))
     result |= 16;
+#endif
   return result;
 ]])],
           [am_cv_func_iconv_works=yes], ,