configure: update the copyright year in the output

configure.ac

@@ -29,7 +29,7 @@ AC_INIT([curl], [-], [a suitable curl mailing list: http://curl.haxx.se/mail/])
 CURL_OVERRIDE_AUTOCONF
 
 dnl configure script copyright
-AC_COPYRIGHT([Copyright (c) 1998 - 2010 Daniel Stenberg, <daniel@haxx.se>
+AC_COPYRIGHT([Copyright (c) 1998 - 2011 Daniel Stenberg, <daniel@haxx.se>
 This configure script may be copied, distributed and modified under the
 terms of the curl license; see COPYING for more details])