crypto/modes/modes_lcl.h: let STRICT_ALIGNMENT be on iOS.

While ARMv7 in general is capable of unaligned access, not all instructions
actually are. And trouble is that compiler doesn't seem to differentiate
those capable and incapable of unaligned access. As result exceptions could
be observed in xts128.c and ccm128.c modules. Contemporary Linux kernels
handle such exceptions by performing requested operation and resuming
execution as is if it succeeded. While on iOS exception is fatal.
Correct solution is to let STRICT_ALIGNMENT be on all ARM platforms,
but doing so is in formal conflict with FIPS maintenance policy.

Reviewed-by: Dr. Stephen Henson <steve@openssl.org>