Clucene: Fixed MSVC2011 build.

Clucene: Fixed MSVC2011 build.

This is basically taken from Qt 4.8 /
69f84b9514f8f22d27590ac890dbd20aec369702.

Clucene is broken in MVS2011 due to changed stdext::hash_map which
is used as the ancestor in inner CLucene classes. It ended up with
names collision and double inheritance from the one base class.
Fix reflects that change.

Change-Id: Ia733c3b51dafc5d22674cc3822e6305819582429
Initial-patch-by: Eugene Shcherbina <eugene@eshcher.com>
Reviewed-by: Karsten Heimrich <karsten.heimrich@nokia.com>