delete autotools .gitignore files

One special case, `src/util/xmlpool/.gitignore` is not entirely deleted,
as `xmlpool.pot` still gets generated (eg. by `ninja xmlpool-pot`).

Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>
60 files changed