Add LSM to the list of data sources for which we don't do verification
or salvage -- I'm betting this will allow test/format to regularly run
LSM tests.

Minor simplification to open/close patterns in the main driver code,
compare against the Berkeley DB data set after salvage, if possible.
Fix a bug on systems without O_CLOEXEC which would silently ignore
O_DIRECT configuration.
Clean up the comments around the laundry list of configuration, no
real change.