COMP: Fix MacOSX build issue when building against Qt 4.7.4. Fixes #3471

Since "QSysInfo::MV_10_8" has been first introduced in Qt 4.8.3,
exclude the fix for issue #3460 introduced in commit r22641.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22657 3bd1e089-480b-0410-8dfb-8563597acbee