Fix T39420: Cycles viewport/preview flickers, when moving mouse across editors

Issue was caused by the wrong usage of OCIO GLSL binding API. To make it
work properly on pre-GLSL-1.3 drivers shader is to be enabled after the
texture is binded to the opengl context. Otherwise it wouldn't know the
proper texture size.

This is actually a regression in 2.70 and to be ported to 'a'.

intern/cycles/render/buffers.h

@@ -31,6 +31,7 @@
 CCL_NAMESPACE_BEGIN
 
 class Device;
+class DeviceDrawParams;
 struct float4;
 
 /* Buffer Parameters
@@ -114,7 +115,7 @@ public:
 	void write(Device *device, const string& filename);
 
 	void draw_set(int width, int height);
-	void draw(Device *device);
+	void draw(Device *device, const DeviceDrawParams& draw_params);
 	bool draw_ready();
 
 	device_memory& rgba_data();