OSProcess file locking bug report and fix

OSProcess file locking bug/fix

Affected platforms:
Squeak applications that rely on file locking for Unix, such as
Omnibase applications. Squeak with OSProcess on Unix/Linux using
unix file locking with Win32 file lock emulation disabled. The
problem does not occur if Win32 file lock emulation is enabled
(OSProcessAccessor emulateWin32FileLocking: true).

Defect:
UnixOSProcessAccessor>>unlockFileRegion: may not unlock a file
or file region when Win32 compatibility is disabled
(OSProcessAccessor emulateWin32FileLocking: false).

Resolution:
Change set attached, "OSProcessFileLockPatch-dtl.2.cs".
An updated SUnit test that demonstrate the problem is at:
  http://www.squeaksource.com/OSProcess/Tests-OSProcess-dtl.14.mcz
The most recent OSProcess (unreleased), including this patch and a
few unrelated updates, is at:
  http://www.squeaksource.com/OSProcess/OSProcess-dtl.21.mcz

If you are not using OSProcess for file locking on a Unix/Linux
platform, you should ignore this update.

Dave