[patch] Correctly align arrays of int64_t on 32 bit systems

[Rafael Espíndola]

> Looks like you're also missing an update to ASTContext.h to change the
> parameter name there?

Oh, I didn't noticed the comment was duplicated. I updated to the
current style by centralizing it in the .h.

> I suspect we'll want to revisit this at some point, but LGTM for now.

Thanks. Committed as r187999.

Cheers,
Rafael