Reset vertex buffer cache at the end of flush

Reset vertex buffer cache at the end of flush

We only check the internal value of VertexBufferBindingDescriptor.

But if the size of mImpl->mCurrentVertexBufferBindings changed, or cleared,
the vertex buffer's pointer might be same as previos old items.
In this case, we might miss vertex attribute, or VAO relative actions.

To avoid this case, let we clear current binded vertex
whenever if the size of mImpl->mCurrentVertexBufferBindings changed.

Change-Id: I8a4081d9ead39ea9927572876e1a6fe50bef376e
Signed-off-by: Eunki, Hong <eunkiki.hong@samsung.com>