fixed race condition at startup

Signature.cpp

@@ -435,8 +435,13 @@ namespace crypto
 	std::unique_ptr<Ed25519>& GetEd25519 ()
 	{
 		if (!g_Ed25519)
-			g_Ed25519.reset (new Ed25519());
-			
+		{
+			auto c = new Ed25519();
+			if (!g_Ed25519) // make sure it was not created already
+				g_Ed25519.reset (c);
+			else
+				delete c;
+		}	
 		return g_Ed25519; 
 	}