Remove compat code for OpenSSL < 0.9.7.

Resyncs that code with OpenBSD upstream.
diff --git a/sshkey.c b/sshkey.c
index 53a7674..3c48784 100644
--- a/sshkey.c
+++ b/sshkey.c
@@ -3513,11 +3513,7 @@
 	int success, r;
 	int blen, len = strlen(_passphrase);
 	u_char *passphrase = (len > 0) ? (u_char *)_passphrase : NULL;
-#if (OPENSSL_VERSION_NUMBER < 0x00907000L)
-	const EVP_CIPHER *cipher = (len > 0) ? EVP_des_ede3_cbc() : NULL;
-#else
- 	const EVP_CIPHER *cipher = (len > 0) ? EVP_aes_128_cbc() : NULL;
-#endif
+	const EVP_CIPHER *cipher = (len > 0) ? EVP_aes_128_cbc() : NULL;
 	const u_char *bptr;
 	BIO *bio = NULL;