sqlite3 dbd provider question

[William A. Rowe, Jr.]

I'm reviewing the providers themselves and trying to determine how and when
the dbd lock api should be used vs. a dso-module apr-util wide mutex should
be used instead.

The oracle provider alone is using this lock to prepare statements.  While
the sqlite3 provider seems to use it much more extensively, and the other
providers aren't using it at all.

Can someone explain the discrepancy, and if they shouldn't be per-provider
mutexes so we aren't blocking in silly ways between providers accessed by
different threads?