rpc: add external signer RPC files

src/wallet/rpcsigner.cpp

@@ -0,0 +1,41 @@
+// Copyright (c) 2018-2021 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <rpc/server.h>
+#include <util/strencodings.h>
+#include <wallet/rpcsigner.h>
+#include <wallet/wallet.h>
+
+#ifdef ENABLE_EXTERNAL_SIGNER
+
+// CRPCCommand table won't compile with an empty array
+static RPCHelpMan dummy()
+{
+    return RPCHelpMan{"dummy",
+                "\nDoes nothing.\n"
+                "",
+                {},
+                RPCResult{RPCResult::Type::NONE, "", ""},
+                RPCExamples{""},
+        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
+{
+    return NullUniValue;
+},
+    };
+}
+
+Span<const CRPCCommand> GetSignerRPCCommands()
+{
+// clang-format off
+static const CRPCCommand commands[] =
+{ // category              actor (function)
+  // --------------------- ------------------------
+  { "signer",              &dummy,                },
+};
+// clang-format on
+    return MakeSpan(commands);
+}
+
+
+#endif // ENABLE_EXTERNAL_SIGNER