Workaround gcc-4.7 bug #53900 (too aggressive optimization in our alignment check)
(transplanted from 74907bb142e913430e1fa5229ade939d07a4e6a9)

--HG--
branch : 3.1
extra : transplant_source : t%90%7B%B1B%E9%13C%0E%1F%A5%22%9A%DE%93%9D%07%A4%E6%A9