When ImpGraphic::ImplSwapOut() is called with null
pointer it was assumed that it is becase the graphic is
a link and so we don't need to swap out it actually (we can
load it anytime using the link), only clear the graphic's
internal data.

The problem with that it can happen that ImplSwapOut()
is called with null pointer accidentally on a non-link
graphic object which leads to that we loose the graphic.
Seems more robust to use an explicit indicator
(GRFMGR_AUTOSWAPSTREAM_LINK) for links swapout.
indicator

Change-Id: Icf31524a192c7866278ba6a13eb85648aa69f554