Otherwise we may be reading outside of the client request.

v2: backport to nx-libs 3.6.x (Mike DePaulo)
v3: port to NXrender.c rather than render.c (Mike DePaulo)
Signed-off-by: Julien Cristau <jcristau@debian.org>
Reviewed-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>

Conflicts:
	render/render.c