NTFS alternate stream + sparse file; Minor tidy-up.

[axelriet]

• Fixed unused labels on Win32.
• Fixed bogus format string in TRACE call.
• MDB_BUGCHECK: Added compile-time option to bugcheck (initiate a memory dump) instead of calling abort() on Win32.
• MDB_NTFSSTREAM: Added option to embed the lock file within the main data file as an NTFS alternate data stream.
• MDB_NTFSSPARSE: Added option to set the data file as sparse on NTFS.

No default behavior was changed by the added options, which are all opt-in. In other words, the code compiles and behaves exactly as before until one of the new options is set.

[tannerdsilva]

This repo is a read-only mirror of the real repo, which is on GitLab.

I wouldn't expect to see any code merges happen here.