* EIGEN_ALIGN and EIGEN_DONT_ALIGN and the corresponding logic in Macros.h
(instead of using EIGEN_ARCH_WANTS_ALIGNMENT)
* The body of ei_aligned_malloc and ei_aligned_free
The reason for this backporting is that a user complained that with eigen 2.0 he got a warning at Memory.h:81 that the return value of posix_memalign was not used, and that function was declared with an attribute warn_unused_result.
Looking at this, it seemed that the body of this function was already overly complicated, and fixing this warning made it even worse, while the devel branch had a much simpler body and didn't suffer from that problem.
Then it was necessary to update ei_aligned_free too, and to backport EIGEN_ALIGN.
Inch' Allah....
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