make ecc_ssh_ecdsa_encode_name conditional on LTC_SSH

This fixes build breakage when LTC_MECC is not defined:

src/pk/ecc/ecc_ssh_ecdsa_encode_name.c:20:74: error: unknown type name 'ecc_key'
   20 | int ecc_ssh_ecdsa_encode_name(char *buffer, unsigned long *buflen, const ecc_key *key)

src/pk/ecc/ecc_ssh_ecdsa_encode_name.c

@@ -8,6 +8,8 @@
    Russ Williams
 */
 
+#ifdef LTC_SSH
+
 /**
   Curve/OID to SSH+ECDSA name string mapping
   @param buffer    [out] The destination for the name
@@ -60,3 +62,4 @@ error:
    return err;
 }
 
+#endif