i965/cfg: Fix end_ip of last basic block.

start_ip and end_ip are inclusive.

Increases instruction counts in 64 shaders in shader-db, likely
indicative of them previously being misoptimized.

src/mesa/drivers/dri/i965/brw_cfg.cpp

@@ -313,7 +313,7 @@ cfg_t::cfg_t(exec_list *instructions)
       }
    }
 
-   cur->end_ip = ip;
+   cur->end_ip = ip - 1;
 
    make_block_array();
 }