Source: autoconf Version: 2.71-3 This package uses the stage1 build profile, which is deprecated according to https://wiki.debian.org/BuildProfileSpec. It probably ought to use the nodoc profile instead, and also tag the build dependencies accordingly.
See #737936 for the reason why the profile was added. The patch there left the build dependencies untouched, most likely because at that time there was no support for build profiles in dpkg.