Bugs fixed:
- Bug #20791 valgrind errors in InnoDB
Remove Valgrind warning of Bug #20791 : in new database
creation, we read the doublewrite buffer magic number from
uninitialized memory; the code worked because it was extremely
unlikely that the memory would contain the magic number
- Bug #21784 DROP TABLE crashes 5.1.12-pre if concurrent
queries on the table
remove update_thd() in ::store_lock()
Also includes numerous coding style fixes, etc. See file-level
comments for details.