ScaledDIBSectionBuffer class improvements:

ScaledDIBSectionBuffer class improvements:
Copy the pixel data from source buffer to scale buffer
if scale was changed to 100 percent and copy the pixel data
from scaled buffer to source buffer if scale was changed
from 100 percent. It allow refresh the Desktop Window
without sending FramebufferUpdateRequest message and
decrease the network traffic.

git-svn-id: svn://svn.code.sf.net/p/tigervnc/code/trunk@597 3789f03b-4d11-0410-bbf8-ca57d06f2519