Add AES-192-OFB.

cryptography.io gets offended if the library supports some OFB sizes but
not others.

Change-Id: I7fc7b12e7820547a82aae84d9418457389a482fe
Reviewed-on: https://boringssl-review.googlesource.com/29204
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/include/openssl/cipher.h b/include/openssl/cipher.h
index 1db81ae..7d99d49 100644
--- a/include/openssl/cipher.h
+++ b/include/openssl/cipher.h
@@ -417,6 +417,7 @@
 OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_192_cbc(void);
 OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_192_ctr(void);
 OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_192_gcm(void);
+OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_192_ofb(void);
 
 // EVP_aes_128_cfb128 is only available in decrepit.
 OPENSSL_EXPORT const EVP_CIPHER *EVP_aes_128_cfb128(void);