Zack Weinberg (upstream) asked for a test rebuild in September: http://qa-logs.debian.net/2020/09/26.ac270/
I filed now bug reports for all affected packages. See: https://bugs.debian.org/cgi-bin/pkgreport.cgi?tag=ftbfs-ac270;users=d...@debian.org There's also an autoconf2.69 package in the NEW queue, which I intend to maintain under the GCC team umbrella.
