Revert AC prereq to allow building on older systems

configure.in

@@ -11,8 +11,8 @@ dnl The Software is provided WITHOUT ANY WARRANTY, EXPRESS OR IMPLIED. This
 dnl notice is a summary of the Click LICENSE file; the license in that file is
 dnl legally binding.
 
-AC_INIT([click],[2.1])
-AC_PREREQ([2.71])
+AC_INIT([click], [2.1])
+AC_PREREQ(2.60)
 AC_CONFIG_HEADERS([include/click/config.h:config.h.in], [echo > stamp-h])
 AC_CONFIG_HEADERS([include/click/pathvars.h:pathvars.h.in])
 AC_CONFIG_HEADERS([include/click/config-bsdmodule.h:config-bsdmodule.h.in include/click/config-linuxmodule.h:config-linuxmodule.h.in include/click/config-ns.h:config-ns.h.in include/click/config-userlevel.h:config-userlevel.h.in include/click/config-minios.h:config-minios.h.in])
@@ -39,7 +39,7 @@ AC_DEFINE_UNQUOTED([CLICK_VERSION_CODE], [CLICK_MAKE_VERSION_CODE($click_version
 CLICK_INIT('$(top_srcdir)')
 
 dnl support for cross compiling
-AC_CANONICAL_TARGET
+AC_CANONICAL_SYSTEM
 
 dnl This is wrong!!
 AC_CHECK_TOOL(CC, gcc)