Don't distribute config.py in source tarball
Don't distribute config.py in source tarball

config.py is analogous to config.h: it's generated at build time based
on the arguments passed to configure. Having it in EXTRA_DIST led to the
interesting situation where `make distcheck` would:

• generate config.py while making the tarball, with DEBUGGING = True;
• generate it again when building, with DEBUGGING = False, but in
  _build/tests/twisted not in tests/twisted;
• fail the debugger test because python picked up the config.py from the
  source tree rather than from the build tree, leading to the test
  trying to use the debugger despite Gabble being built without it.

Reviewed-by: Simon McVittie <2b470b34502dbf3ba4bcc04ea7e64f4e0e104f33@collabora.co.uk>

community-ssu/telepathy-gabble,community-ssu/telepathy-gabble,community-ssu/telepathy-gabble,community-ssu/telepathy-gabble