[Bug middle-end/64247] malloc alignment and -mavx

[Joost.VandeVondele at mat dot ethz.ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64247

--- Comment #6 from Joost VandeVondele <Joost.VandeVondele at mat dot ethz.ch> 
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some similarity with the problem discussed PR55916, except that this case
doesn't require __float128