Move OPENSSL_SMALL_FOOTPRINT-related logic from aligned_alloc to the only caller

Move OPENSSL_SMALL_FOOTPRINT-related logic from aligned_alloc to the only caller

Originally, CRYPTO_aligned_alloc() returned NULL if OpenSSL was built
with OPENSSL_SMALL_FOOTPRINT defined, which is a weird place for such
a consideration;  moreover it means that every caller requires to
implement some form of a fallback (and manually over-allocate
and then align the returned memory if the alignment is a requirement),
which is counter-productive (and outright ridiculous in environments
with posix_memalign() available).  Move the OPENSSL_SMALL_FOOTPRINT
consideration to the only current caller and update the documentation
and tests accordingly.

Signed-off-by: Eugene Syromiatnikov <esyr@openssl.org>
Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Saša Nedvědický <sashan@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/28295)