Log Message:
Do not intermingle build phases, CONFIGURE_DIRS can specify a list of
directories to process. The removal of pre-configure fixes the config.*
handling at the same time. Also specify the config.status overrides.
Patch configure to not try to detect -lrfftw, just link the static
version explicitly. Do the same for -lfftw. This ensures that we
actually do get the static versions without having to worry about
libtool being too clever. Retire manual config.sub hacks, this should be
handled by config.guess already.

<jlam> just go ahead and commit that benchfft patch and let's
<jlam> never speak of it again :)