Cherry pick r71407 by Trevor Thompson:
- Rewrote FsRtlGetNextBaseMcbEntry(), FsRtlLookupBaseMcbEntry(), and FsRtlNumberOfRunsInBaseMcb() using simpler logic.
This finally fixes broken MCB handling in ReactOS and allows FSDs relying on MCB to properly work in ReactOS!
CORE-11002 #resolve #comment Fixed in r71409
svn path=/trunk/; revision=71409