Instead iterating through all rows to get the number of hidden items,
iterate over the hidden items which are fewer items.
Also don't create a temporary vector with visible flow positions by
remembering the count of hidden items before the working index and
adjusting them appropriately which gives a significant performance
boost when working with a large data set.
[ChangeLog][QtWidgets][QListWidget] Speedup handling of hidden items
when working with large data sets
Task-number: QTBUG-68977
Change-Id: I599b6e97945c245f02229145baad8363ec2bf2f5
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>
Move all widget-dependent benchmarks which were still in gui
subdirectory to widgets
Task-number: QTBUG-23129
Change-Id: I1359f1ea4036cacdfdbe08ff9ecdf1e2c75a005b
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>
