use 8k buffers to match the default on the file servers

Reference: /n/atom/patch/applied2013/cwfsbufsz
Date: Wed Jun 19 21:51:29 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/cmd/cwfs/cwfs/dat.h	Wed Jun 19 21:51:20 2013
+++ /sys/src/cmd/cwfs/cwfs/dat.h	Wed Jun 19 21:51:20 2013
@@ -7,7 +7,7 @@
  * the number of elements in a free-list-block array.
  */
 #ifndef RBUFSIZE
-#define RBUFSIZE	(16*1024)	/* raw buffer size */
+#define RBUFSIZE	(8*1024)	/* raw buffer size */
 #endif
 #include "32bit.h"
 /*