Use the log sync setting to decide whether to sync the directory on log file creation.
Let logging manage syncing the directory itself #1343
Add SLOT_SYNC_DIR to sync directory on both dsync and fsync. #1343
Fix loop conditions since it now includes SLOT_SYNC_DIR. #1343
Move directory sync code into os_fsync.c, only sync directories when creating files.
Bump release version to 2.4.2 on develop branch.
If forcing a busy page out of memory, it's possible reconciliation couldn't
write any key/value pairs, in which case we have a page image with no items.
In that case, pass in an additional flag to verification that an empty page
is OK.

Reference #1347.
Merge branch 'develop' into directory-sync-log-files
Simplify the directory/file sync loop, clean up a few cases where we
were ignoring error returns.
Merge pull request #1348 from wiredtiger/directory-sync-log-files-loop

Simplify the directory/file sync loop
Initialize sync_dir_lsn to zero, not one. #1343
Keep an open file handle on the log directory. #1343
Fix error message. #1343
Remove debug verbose message.
ERR->RET
Move initialization of direct_io.
KNF
Fix table updates with custom extractor.  We were stashing a copy of the new value in the table cursor value, but that copy was being overwritten when invoking the custom extractor.

refs #1199
Avoid the "bool" flavor of compare-and-swap primitives: clang 3.5.0 produces bad code.
Flush checkpoint handles prior to taking schema lock.

This should save time when flushing again while holding the schema lock.