svga: fix pre-mature flushing of the command buffer

svga: fix pre-mature flushing of the command buffer

When surface_invalidate is called to invalidate a newly created surface
in svga_validate_surface_view(), it is possible that the command
buffer is already full, and in this case, currently, the associated wddm
winsys function will flush the command buffer and resend the invalidate
surface command. However, this can pre-maturely flush the command buffer
if there is still pending image updates to be patched.

To fix the problem, this patch will add a return status to the
surface_invalidate interface and if it returns FALSE, the caller will
call svga_context_flush() to do the proper context flush.
Note, we don't call svga_context_flush() if surface_invalidate()
fails when flushing the screen surface cache though, because it is
already in the process of context flush, all the image updates are already
patched, calling svga_context_flush() can trigger a deadlock.
So in this case, we call the winsys context flush interface directly
to flush the command buffer.

Fixes driver errors and graphics corruption running Tropics. VMware bug 1891975.

Also tested with MTT glretrace, piglit and various OpenGL apps such as
Heaven, CinebenchR15, NobelClinicianViewer, Lightsmark, GoogleEarth.

cc: mesa-stable@lists.freedesktop.org
Reviewed-by: Brian Paul <brianp@vmware.com>