Stored TA command stream persists on TA_LIST_INIT, until first actual write.

Fixes #141, "Main menus on POD and Speed Devil show up black"

Seems like the TA doesn't touch any of the memory structures before first write (and probably later on, but we're not gonna support corrupted ta streams for now)

According to p1pkin

«At least in SpeedDevils, at title screen game do a bit weird thing
 - Init TA context
 - Send lists to TA
 - Init the same context again
 - Start Render

so, if you are clear stored poly/vertex data at "TA_LIST_INIT" pvr2 reg write - you'll get black screen instead game title»

core/hw/pvr/ta_ctx.h

@@ -146,7 +146,11 @@ struct TA_context
 
 	void MarkRend()
 	{
+<<<<<<< HEAD
 		rend.proc_start = tad.thd_root;
+=======
+		rend.proc_start = rend.proc_end;
+>>>>>>> Stored TA command stream persists on TA_LIST_INIT, until first actual write.
 		rend.proc_end = tad.End();
 	}
 	void Alloc()