Hi. It would appear that the qt-webkit ebuild builds the copy of sqlite included in qt for some reason. This isn't really optimal since looking at the qt-sql ebuild I see that there is some logic to use the system sqlite, which gets bypassed this way. Also for the qt-sql ebuild you have the option to use the -sqlite use flag, which doesn't get respected in the qt-webkit ebuild. For myself I copied the qt-webkit ebuild to a local overlay and added -system-sqlite to the myconf variable in the ebuild, and it seems to work fine and build qt-webkit against the system sqlite rather than building its own copy of sqlite.
Indeed, we should really use the system copy of sqlite, rather than the bundled one.
fixed in qt-webkit-4.6.3-r2 and qt-webkit-4.7.0-r1. thanks for reporting :)
