Use AC_REQUIRE() instead of directly using a macro, the latter doesn't work with autoconf 2.65. This is a backport of r1337 from bakefile svn to allow people to use autoconf 2.65 immediately and will become unnecessary when we update to the next bakefile version. git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@64620 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775