A C11 defect report changed the description of aligned_alloc() so that
it is no longer necessary for the allocation size to be a multiple of
the alignment. Although this isn't yet reflected in the GNU C Library
manual, I'm preparing a patch for them as well.

Here is the DR:
http://www.open-std.org/jtc1/sc22/wg14/www/docs/summary.htm#dr_460