many: fix remaining check-pointer-deref issues

The updated parsing_hacks.h file uncovered a bunch of extra
things that the check-pointer-deref coccinelle script flags.

This commit fixes them to make the tree check-pointer-deref clean.

src/shared/install-printf.c

@@ -12,6 +12,8 @@ static int specifier_prefix_and_instance(char specifier, const void *data, const
         _cleanup_free_ char *prefix = NULL;
         int r;
 
+        assert(ret);
+
         r = unit_name_to_prefix_and_instance(i->name, &prefix);
         if (r < 0)
                 return r;