curve448/field.h: relax alignment, as it doesn't work universally.
Some platforms, cough-DJGPP, fail to compile claiming that requested
alignment is greater than maximum possible. Supposedly original
alignment was result of an attempt to utilize AVX2...
# if defined(__GNUC__) || defined(__clang__)
# define INLINE_UNUSED __inline__ __attribute__((__unused__,__always_inline__))
# define RESTRICT __restrict__
-# define ALIGNED __attribute__((__aligned__(32)))
+# define ALIGNED __attribute__((__aligned__(16)))
# else
# define INLINE_UNUSED ossl_inline
# define RESTRICT
