For any given class currently we copy the vtable data from the root to the
parent of the klass. As already the parent class has done the same for itself
we can just copy from the parent class no need to build from scratch.
The issue with building from scratch is that we will endup with more unique table
because of table_merge logic and unique slot index.
testenv : elementary_test
This patch creates 55 fewer table than before = 26KB in 64bit sysytem.