libgcrypt-1.5: rinjdael: Fix use of SSE2 outside USE_AESNI/ctx->use_aesni

* cipher/rijndael.c (_gcry_aes_cbc_enc, _gcry_aes_cbc_dec): Check if
AES-NI is enabled before calling aesni_prepare() and aesni_cleanup().

aesni_cleanup() contains SSE2 instructions that are interpreted as MMX on CPUs
without SSE2 support (Pentium-III, etc). In above functions, aesni_cleanup()
was called outside use_aesni checks. This causes x87 register state to be
poisoned, causing crashes later on when program tries to use floating point
registers.

Add missing '#ifdef USE_AESNI' and 'if (ctx->use_aesni)' for aesni_cleanup()
and, while at it, for aesni_prepare() too.

• Reported-by: Mitsutoshi NAKANO <bkbin005@rinku.zaq.ne.jp>
• Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>