[V8] Fix stack alignment corruption for MinGW32 build

BUG: https://bugreports.qt-project.org/browse/QTBUG-31396

Change-Id: If9b236f24ed82f4b6b19a2af938b422c68e5eab8
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
(cherry picked from commit 91f936a862644c7ca7a1762ad05cc91d263b808e)
Reviewed-by: Peter Varga <pvarga@inf.u-szeged.hu>
Reviewed-by: Liang Qi <liang.qi@digia.com>