DRASCULA: Fix Missing Default Switch Cases

These are flagged by GCC if -Wswitch-default is enabled.

engines/drascula/graphics.cpp

@@ -236,6 +236,7 @@ void DrasculaEngine::print_abc(const char *said, int screenX, int screenY) {
 
 				switch (_charMap[i].charType) {
 				case 0:		// letters
+				default:
 					letterY = (_lang == kSpanish) ? 149 : 158;
 					break;
 				case 1:		// signs