gpg: When the TOFU DB is in batch mode, periodically drop the locks.
* g10/tofu.c: Include <sched.h>. (batch_update_started): New variable. (begin_transaction): If we've been in batch mode for a while, then commit any extant batch transactions. (tofu_begin_batch_update): If we are not in batch mode, initialize batch_update_started.
- Signed-off-by: Neal H. Walfield <neal@g10code.com>