Fully qualify friend class in autogenerated table code

Otherwise MSVC doesn't recognize it as friend. For some reason it worked
on GCC and clang.

This fixes the standalone build with MSVC.

Change-Id: Id61694cbb1c91c6dad8b1b8abae68c5390abed78
diff --git a/python/generators/trace_processor_table/serialize.py b/python/generators/trace_processor_table/serialize.py
index 1b498c3..e9629d7 100644
--- a/python/generators/trace_processor_table/serialize.py
+++ b/python/generators/trace_processor_table/serialize.py
@@ -401,7 +401,8 @@
 
    private:
     friend class {self.table_name};
-    friend class AbstractConstIterator;
+    friend class macros_internal::AbstractConstIterator<
+      ConstIterator, {self.table_name}, RowNumber, ConstRowReference>;
   }};
       '''