use CreateDirectoryA in test.cpp

(weren't we supposed to use unicode functions in this file??? idk
whatever, i'm just copying delete_file() here)

src/asar-tests/test.cpp

@@ -413,7 +413,7 @@ static void delete_file(const char * filename)
 static void create_directory(const char * dirname)
 {
 #ifdef _WIN32
-	CreateDirectory(dirname, NULL);
+	CreateDirectoryA(dirname, NULL);
 #else
 	mkdir(dirname, 0777);
 #endif