Fixed double free() in level1v example (#482)

Details:
- In exampls/tapi/00level1v.c, pointer 'z' was being freed twice and
  pointer 'a' was not being freed at all. This commit correctly frees 
  each pointer exactly once.

examples/tapi/00level1v.c

@@ -175,7 +175,7 @@ int main( int argc, char** argv )
 	free( y );
 	free( z );
 	free( w );
-	free( z );
+	free( a );
 
 	return 0;
 }