tests/test-fuzz-targets.t

contrib: remove fixpax.py

This was used as part of bdist_mpkg. And we stopped using bdist_mpkg
after db5084d27df5.

Differential Revision: https://phab.mercurial-scm.org/D3539

#require clang-libfuzzer test-repo
  $ cd $TESTDIR/../contrib/fuzz
  $ make
Just run the fuzzer for five seconds to verify it works at all.
  $ ./bdiff -max_total_time 5