Repair for non-ECC OpenSSL.

Ifdef out the ECC parts when building with an OpenSSL that doesn't have
it.
diff --git a/ssh_api.c b/ssh_api.c
index ca4789b..6c71258 100644
--- a/ssh_api.c
+++ b/ssh_api.c
@@ -105,7 +105,9 @@
 		ssh->kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
 		ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
 		ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
+# ifdef OPENSSL_HAS_ECC
 		ssh->kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
+# endif
 #endif /* WITH_OPENSSL */
 		ssh->kex->kex[KEX_C25519_SHA256] = kexc25519_server;
 		ssh->kex->load_host_public_key=&_ssh_host_public_key;
@@ -117,7 +119,9 @@
 		ssh->kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
 		ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
 		ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
+# ifdef OPENSSL_HAS_ECC
 		ssh->kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
+# endif
 #endif /* WITH_OPENSSL */
 		ssh->kex->kex[KEX_C25519_SHA256] = kexc25519_client;
 		ssh->kex->verify_host_key =&_ssh_verify_host_key;