Use cgit downloads for GNU config scripts

Co-authored-by: brettcannon <54418+brettcannon@users.noreply.github.com>

Author: Copilot

autoconf/Dockerfile

@@ -3,9 +3,9 @@ FROM docker.io/library/ubuntu:24.04
 ARG AUTOCONF_VERSION="2.72"
 ARG AUTOCONF_ARCHIVE_VERSION="2023.02.20"
 ARG AUTOMAKE_VERSION="1.16.5"
-# config.guess and config.sub are vendored from revision
-# 00b15927496058d23e6258a28d8996f87cf1f191 of
-# https://git.savannah.gnu.org/git/config.git.
+# Specific revision of https://git.savannah.gnu.org/git/config.git
+# for config.guess and config.sub.
+ARG CONFIG_GIT_REV="00b15927496058d23e6258a28d8996f87cf1f191"
 
 LABEL org.opencontainers.image.source="https://github.com/python/cpython-devcontainers"
 LABEL org.opencontainers.image.base.name="docker.io/library/ubuntu:24.04"
@@ -46,8 +46,10 @@ RUN PATCH_VERBOSE=1 curl https://ftp.gnu.org/gnu/autoconf-archive/autoconf-archi
     && ./configure --prefix=/usr/local \
     && make \
     && make install
-COPY --chmod=755 config.guess /usr/local/share/autoconf/build-aux/config.guess
-COPY --chmod=755 config.sub /usr/local/share/autoconf/build-aux/config.sub
+ADD --chmod=755 https://git.savannah.gnu.org/cgit/config.git/plain/config.guess?id=${CONFIG_GIT_REV} \
+    /usr/local/share/autoconf/build-aux/config.guess
+ADD --chmod=755 https://git.savannah.gnu.org/cgit/config.git/plain/config.sub?id=${CONFIG_GIT_REV} \
+    /usr/local/share/autoconf/build-aux/config.sub
 COPY config.sub.patch .
 RUN p=$(pwd)/config.sub.patch \
     && cd /usr/local/share/autoconf/build-aux \