There is an issue with the chicken-4.9.0.1 tarball (which was never bootstrapped in Fedora, presumably due to being a micro point release) which prevents it from being bootstrapped. This prevents bootstrapping chicken on new EPEL architectures. If a rebase to 4.10 (which apparently does bootstrap) is not planned for epel7, then the workaround is to add an "%else\ntouch data-structures.c" to the bootstrap conditional which precedes make.
It's bootstrapped now.