reset alignment at inheritence boundary when iterating over fields

In type-generator, we were incorrectly calculating field offsets where
a class inherits from another class whose last field has a natural
alignment which is different from the native word size.  Surprisingly,
this only popped up when I built using the Android class library on a
64-bit system.

src/tools/type-generator/main.cpp

@@ -662,6 +662,7 @@ class MemberIterator {
           assert(member->type == Object::Scalar);
           offset_ = ((offset_ + size_) + (BytesPerWord - 1))
             & ~(BytesPerWord - 1);
+          alignment_ = BytesPerWord;
           member = 0;
         }