Fix aesni_cbc_sha256_enc_avx2 backtrace info

We store a secondary frame pointer info for the debugger
in the red zone.  This fixes a crash in the unwinder when
this function is interrupted.

Additionally the missing cfi function annotation is added
to aesni_cbc_sha256_enc_shaext.

[extended tests]

Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/10674)
