Merge 296424 from stable/10 - contains the following changes to -current:
r295924: Make sure that hash-based db files fsync befor closing/syncing.
r295925: We no longer need O_SYNC pwd_mkd
r295465: We no longer need O_SYNC on services_mkdb
r295800: We no longer need O_SYNC on cap_mkdb
Approved by: re (marius)