This reverts commit f647375275. There are
no signed integer overflows in atomics.
For the non-atomic side, unlike the commit being reverted, we fix the
signed integer overflow by removing the "signed" part instead of the
"overflow" part, and use unsigned integer overflows instead.
Change-Id: I53335f845a1345299031fffd176f5ba479163e44
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>