Partially revert "Fix a deadlock introduced by the race condition fix"

The commit was 9361be58f47ec256bf920c378479a02501219c1f (2008-11-17),
referring to the race condition fix that was applied in commit
d47c05b1889bb4f06203bbc65f4660b8d0128954 (2008-10-08). The fix for the
deadlock reintroduced the race condition and the commit message noted
it.

The workaround is no longer necessary since we've fixed the original race
condition differently now (see the previous two commits).

Task-number: QTBUG-42189
Change-Id: I5a83249597a83c4d4caa2ae57964ad3cc61c1d70
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@digia.com>
Reviewed-by: Albert Astals Cid <albert.astals@canonical.com>
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@theqtcompany.com>