Rename configure.in and configure-libafs.in to use the *.ac extension
instead, which is preferred by current Autoconf versions for input
files to Autoconf. *.in can then be more consistently used for files
that are input into config.status.
Change-Id: I4d352560200e4dbb1a2dda3d5ab7c7c9a38b565f
Reviewed-on: http://gerrit.openafs.org/2437
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Russ Allbery <rra@stanford.edu>
