From build.log:

+ /usr/bin/make -O -j2 V=1 VERBOSE=1 V=1 -f makefile docs
/usr/bin/make -C doc/ docs V=1
make[1]: Entering directory '/builddir/build/BUILD/libtomcrypt-1.18.2/doc'
rm -f crypt.pdf *.dvi *.log *.aux *.toc *.idx *.ilg *.ind *.out *.lof
cp crypt.tex crypt.bak
touch -r crypt.tex crypt.bak
(printf "%s" "\def\fixedpdfdate{"; date +'D:%Y%m%d%H%M%S%:z' -d @$(stat --format=%Y crypt.tex) | sed "s/:\([0-9][0-9]\)$/'\1'}/g") > crypt-deterministic.tex
printf "%s\n" "\pdfinfo{" >> crypt-deterministic.tex
printf "%s\n" "  /CreationDate (\fixedpdfdate)" >> crypt-deterministic.tex
printf "%s\n}\n" "  /ModDate (\fixedpdfdate)" >> crypt-deterministic.tex
cat crypt.tex >> crypt-deterministic.tex
mv crypt-deterministic.tex crypt.tex
touch -r crypt.bak crypt.tex
echo "hello" > crypt.ind
latex crypt 
This is pdfTeX, Version 3.14159265-2.6-1.40.21 (TeX Live 2020) (preloaded format=latex)
 restricted \write18 enabled.
entering extended mode
(./crypt.tex
LaTeX2e <2020-02-02> patch level 5
pdfTeX warning (\pdfinfo): not allowed in DVI mode (\pdfoutput <= 0); ignoring 
it
(/usr/share/texlive/texmf-dist/tex/latex/base/book.cls
Document Class: book 2019/12/20 v1.4l Standard LaTeX document class
(/usr/share/texlive/texmf-dist/tex/latex/base/bk10.clo))
! LaTeX Error: File `geometry.sty' not found.

This has nothing in common with the new autoconf. We can see the same failure in F35 with the old autoconf.

This is probably triggered by upgrading texlive-latex from 7:20200327-14.fc33 to 9:20200327-28.fc34 <https://koschei.fedoraproject.org/build/9816233>.

doc/crypt.tex:

\documentclass[synpaper]{book}
\usepackage{geometry}

# dnf -q repoquery --whatprovides 'tex(geometry.sty)'
texlive-geometry-9:svn54080-38.fc35.noarch

It's a missing build-time dependency in libtomcrypt.spec.

FEDORA-2021-b76f18ca98 has been submitted as an update to Fedora 34. https://bodhi.fedoraproject.org/updates/FEDORA-2021-b76f18ca98

FEDORA-2021-b76f18ca98 has been pushed to the Fedora 34 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --advisory=FEDORA-2021-b76f18ca98`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2021-b76f18ca98

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

FEDORA-2021-b76f18ca98 has been pushed to the Fedora 34 stable repository.
If problem still persists, please make note of it in this bug report.