Support for the ARM 64 bit CPU architecture (aarch64) was introduced in autoconf 2.69. adonthell appears to use an earlier version of autoconf, preventing its being built. This can be fixed in of three ways (In order of preference): 1. Work with upstream to migrate the package to autoconf 2.69. 2. Rerun autoconf or autoreconf in %prep or %build prior to running configure. 3. Apply the patch at http://ausil.fedorapeople.org/aarch64/adonthell/adonthell-aarch64.patch which updates config.guess and config.sub to recognize aarch64.
There probably won't be any new release of adonthell before a while, as upstream has been working for a long time now on the new version, which is quite ambitious and they have extremely few developers. So option 1 doesn't seem likely (at least not for the current version). Option 2 could become nasty very quickly, if they use old/deprecated stuff in their autotools stuff, and again, they probably wouldn't be interested in the fixes for this version. So option 3 seems like the best way for this package. I don't quite understand what the patch does, and I have no idea about aarch64, so if you're a provenpackager, feel free to just go ahead and apply the patch and rebuild. :)