tests/basics/iter1.py: Add more tests for walking a user-defined iter.

Some code in mp_iternext() was only tested by the native emitter, so the
tests added here test this function using just the bytecode emitter.

tests/basics/iter1.py

@@ -68,3 +68,12 @@ except StopIteration:
 
 for i in myiter(32):
     print(i)
+
+# repeat some of the above tests but use tuple() to walk the iterator (tests mp_iternext)
+print(tuple(myiter(5)))
+print(tuple(myiter(12)))
+print(tuple(myiter(32)))
+try:
+    tuple(myiter(22))
+except TypeError:
+    print('raised TypeError')