[autotests] tst_qmenubar fails too often in CI

The tst_qmenubar autotest has failed 16 times in CI between 2013-03-25 and 2013-04-8, and ranks as one of the top most failing test in that time frame. It seems likely that the test needs fixing.

Most common failure: tst_QMenuBar::task256322_highlight() Compared pointers are not the same

See more info in the following test results:

• http://testresults.qt-project.org/ci/QtBase_stable_Integration/build_00761/macx-clang_developer-build_qtnamespace_OSX_10.7/log.txt.gz
• http://testresults.qt-project.org/ci/Qt5_stable_Integration/build_00127/macx-clang_developer-build_qtnamespace_OSX_10.7/log.txt.gz
• http://testresults.qt-project.org/ci/Qt5_stable_Integration/build_00132/macx-clang_developer-build_qtnamespace_OSX_10.7/log.txt.gz
• http://testresults.qt-project.org/ci/Qt5_stable_Integration/build_00139/macx-clang_developer-build_qtnamespace_OSX_10.7/log.txt.gz
• http://testresults.qt-project.org/ci/Qt5_stable_Integration/build_00140/macx-clang_developer-build_qtnamespace_OSX_10.7/log.txt.gz
• http://testresults.qt-project.org/ci/Qt5_stable_Integration/build_00143/macx-clang_developer-build_qtnamespace_OSX_10.7/log.txt.gz
• http://testresults.qt-project.org/ci/QtBase_dev_Integration/build_00773/macx-clang_developer-build_qtnamespace_OSX_10.7/log.txt.gz
• http://testresults.qt-project.org/ci/Qt5_stable_Integration/build_00149/macx-clang_developer-build_qtnamespace_OSX_10.7/log.txt.gz