6f37f83a48
bug:2683001
implmentation details:
1.close() on any sql statement is should simply queued up for finalization
to be performed later. caller doesn't acquire database lock.
2. the only effect of NOT close immediately is non-release of some memory.
3. all such queued-up-finalizations are performed whenever there is
another execute() of some sql statement on that database from ANY
thread in the process.
4. database close() automatically releases all unfinalized statements
before closing the database.
Change-Id: If4c9c7fde6b8945a41abc6c8b992aa8c69854512