Enable SELECT query planning tracing when compiled with 
SQLITE_ENABLE_SELECTTRACE and either SQLITE_DEBUG or SQLITE_TEST.
Fix the SELECTTRACE_ENABLE macro so that it doesn't cause problems for
testfixture.  Add new SELECTTRACE() calls.
Candidate fix for [d11a6e908f].
Improved ".selecttrace" output.
Add the "showauth" extension in ext/misc.
Add test cases for ticket [89398880bcfff9].
Correctly handle an ORDER BY clause on an outer query when applying
the compound-subquery flattening optimization.  Ticket [89398880bcfff].
Also add the SQLITE_ENABLE_SELECTTRACE option for additional debugging
and analysis information about select statement processing.
Disable shared memory operations using the unix-nolock VFS.