Errors and warnings are processed in IStatus independently. Completion code
is moved away from IStatus and returned directly by appropriate functions.
Replaced isSuccess() with more generic function getStatus(), which sets
appropriate bits in returned value when errors/warnings are present.
Also use same style when returning bytes' array and it's length in different
interfaces.
1. Frontported fix for CORE-3935 and CORE-3993.
2. Added debugging support for mutexes and rwlocks in Vulcan style.
Unfortunately after last 'svn up' build asserts in JrdStatement:71.
2) Reworked the lock manager synchronization: added the RAII mutex holders and avoided dirty reads for the shared memory.
3) Encapsulated lck_length into the Lock class + small related refactoring.
4) Front ported recent fixes from the v2.x branches.
5) Misc cleanup.
Also some cleanups, the most important are:
- meaningful ctor on Jrd::Lock, helping to avoid code dup
- avoid unneeded h-file dependencies, making boot build engine dependent
