use a fake argc/argv to ruby_sysinit()

main.c

@@ -17,7 +17,10 @@ static VALUE eval(const char * string)
 
 int main(int argc, char *argv[])
 {
-    ruby_sysinit(&argc, &argv);
+    int _argc = 1;
+    char *_argv[] = {"main"};
+    char **_argv_p = &_argv[0];
+    ruby_sysinit(&_argc, &_argv_p);
     {
         RUBY_INIT_STACK;
         ruby_init();