The attached patch adds support for pkg-config. This simplifies lots of things, especially when building freeglut as a static library.
We are using this patch (with the slight modification of adding -DFREEGLUT_STATIC to the Cflags) successfully in the mingw-cross-env (MXE) project: http://hg.savannah.gnu.org/hgweb/mingw-cross-env/file/tip/src/freeglut-1-fixes.patch
Please consider including it.
Also, it would be great if that patch could be improved to automatically add -DFREEGLUT_STATIC to the Cflags section whenever ./configure is run with "--enable-static" and "--disable-shared". However, I'm not sure how what's the cleanest way to incorporate this into your configure.ac. However, I think the patch is a great improvement over the current situation even without that conditional.