Stabilize tst_QMenu::statusTip().

Instantiate the timer on the stack to prevent it from
interfering with other tests.

Change-Id: I91ffe23b502fcddaeb6d6d3f89ea3d27b083cdb0
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Fix some compiler warnings in benchmark tests.

main.cpp(332) : warning C4307: '*' : integral constant overflow
tst_qpainter.cpp(1293) : warning C4305: '+=' : truncation from 'double' to 'float'
tst_qpainter.cpp(1474) : warning C4305: '+=' : truncation from 'double' to 'float'
tst_qtbench.cpp(155) : warning C4267: 'initializing' : conversion from 'size_t' to 'int', possible loss of data
main.cpp(68) : warning C4189: 'fontHeight' : local variable is initialized but not referenced

Change-Id: If6aadd50df7c5cf7d0f33791c9247730a47ddd27
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>