[iter][test] Add another test for hb_reduce

Different initial and accumulator types

src/test-iter.cc

@@ -181,6 +181,12 @@ main (int argc, char **argv)
   ;
   // The result should be something like 0->10, 1->11, ..., 9->19
   assert (hb_map_get (result, 9) == 19);
+  
+  unsigned int temp3 = 0;
+  + hb_iter(src)
+  | hb_map([&] (int i) -> int { return ++temp3; })
+  | hb_reduce([&] (float acc, int value) -> float { return acc + value + .05; }, 0)
+  ;
   hb_map_destroy (result);
 
   + hb_iter (src)