added gmtime_r check

configure.in

@@ -469,6 +469,8 @@ else
   dnl is there a localtime_r()
   CURL_CHECK_LOCALTIME_R()
 
+  AC_CHECK_FUNCS( gmtime_r )
+
 fi
 
 dnl **********************************************************************

lib/http.c

@@ -735,7 +735,7 @@ CURLcode Curl_http(struct connectdata *conn)
        * equal to UTC (Coordinated Universal Time)." (see page 20 of RFC2616).
        */
 
-#ifdef HAVE_LOCALTIME_R
+#ifdef HAVE_GMTIME_R
       /* thread-safe version */
       /* We assume that the presense of localtime_r() proves the presense
          of gmtime_r() which is a bit ugly but might work */