Yes xorg-x11-util-macros actually only installs those two macro files I posted earlier.
I may have been missing the server-devel package, but still I'm getting the same error. The package xorg-x11-server-devel does include an aclocal/xorg-server.m4 file, which DOES include the XORG_DRIVER_CHECK_EXT definition:
Despite now having that macro defined, I still get the same message, regarding ./configure.
cat /usr/share/aclocal/xorg-server.m4 | grep XORG_DRIVER_CHECK_EXT