This change makes it safe to call EVP_AEAD_CTX_cleanup after a failed
EVP_AEAD_CTX_init.

Change-Id: I608ed550e08d638cd7e941f5067edd3da4c850ab
Reviewed-on: https://boringssl-review.googlesource.com/4692
Reviewed-by: David Benjamin <davidben@chromium.org>
Reviewed-by: Adam Langley <agl@google.com>

(The huge if-else was hard to visually parse.)

Change-Id: Ic2c94120f345085b619304181e861f662a931a29
Reviewed-on: https://boringssl-review.googlesource.com/4691
Reviewed-by: David Benjamin <davidben@chromium.org>
Reviewed-by: Adam Langley <agl@google.com>

Change-Id: I119929177d3c2135778b567f89923784a3a730ae
Reviewed-on: https://boringssl-review.googlesource.com/4706
Reviewed-by: Adam Langley <agl@google.com>