window: don't add encrypted prompts to input history

NEWS

@@ -1,6 +1,7 @@
 ncmpcpp-0.6.3 (????-??-??)
 
 * Fix floating point exception when adding a specific number of random items.
+* Passwords are no longer added to the input history.
 
 ncmpcpp-0.6.2 (2014-12-13)
 

src/window.cpp

@@ -820,7 +820,7 @@ std::string Window::getString(const std::string &base, size_t width, bool encryp
 	curs_set(0);
 	if (input != nullptr)
 	{
-		if (input[0] != 0)
+		if (!encrypted && input[0] != 0)
 			add_history(input);
 		result = input;
 		free(input);