libbb: make bb_common_bufsiz1 1 kbyte, add capability to use bss tail for it

The config item is FEATURE_USE_BSS_TAIL. When it is off (default):

function                                             old     new   delta
read_config                                          210     228     +18
doCommands                                          2279    2294     +15
ipneigh_list_or_flush                                763     772      +9
ipaddr_list_or_flush                                1256    1261      +5
display_process_list                                1301    1306      +5
conspy_main                                         1378    1383      +5
do_lzo_compress                                      352     355      +3
do_lzo_decompress                                    565     567      +2
push                                                  46      44      -2
inetd_main                                          2136    2134      -2
uevent_main                                          421     418      -3
addLines                                              97      92      -5
bb_common_bufsiz1                                   8193    1024   -7169
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 8/5 up/down: 62/-7181)        Total: -7119 bytes
   text	   data	    bss	    dec	    hex	filename
 829850	   4086	   9080	 843016	  cdd08	busybox_old
 829901	   4086	   1904	 835891	  cc133	busybox_unstripped

FEATURE_USE_BSS_TAIL=y:

read_config                                          210     228     +18
doCommands                                          2279    2294     +15
ipneigh_list_or_flush                                763     772      +9
ipaddr_list_or_flush                                1256    1261      +5
display_process_list                                1301    1306      +5
conspy_main                                         1378    1383      +5
do_lzo_compress                                      352     355      +3
do_lzo_decompress                                    565     567      +2
inetd_main                                          2136    2134      -2
bb_common_bufsiz1                                   8193       -   -8193
------------------------------------------------------------------------------
(add/remove: 0/1 grow/shrink: 8/1 up/down: 62/-8195)        Total: -8133 bytes
   text	   data	    bss	    dec	    hex	filename
 829850	   4086	   9080	 843016	  cdd08	busybox_old
 829911	   4086	    880	 834877	  cbd3d	busybox_unstripped

FIXME: setup_common_bufsiz() calls are missing.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/networking/libiproute/ipaddress.c b/networking/libiproute/ipaddress.c
index 5c975d8..2c0f514 100644
--- a/networking/libiproute/ipaddress.c
+++ b/networking/libiproute/ipaddress.c
@@ -13,6 +13,7 @@
 #include <net/if_arp.h>
 
 #include "ip_common.h"  /* #include "libbb.h" is inside */
+#include "common_bufsiz.h"
 #include "rt_names.h"
 #include "utils.h"
 
@@ -39,7 +40,7 @@
 } FIX_ALIASING;
 typedef struct filter_t filter_t;
 
-#define G_filter (*(filter_t*)&bb_common_bufsiz1)
+#define G_filter (*(filter_t*)bb_common_bufsiz1)
 
 
 static void print_link_flags(unsigned flags, unsigned mdown)
diff --git a/networking/libiproute/ipneigh.c b/networking/libiproute/ipneigh.c
index 179505c..151d3d1 100644
--- a/networking/libiproute/ipneigh.c
+++ b/networking/libiproute/ipneigh.c
@@ -8,6 +8,7 @@
  */
 
 #include "ip_common.h"  /* #include "libbb.h" is inside */
+#include "common_bufsiz.h"
 #include "rt_names.h"
 #include "utils.h"
 #include <linux/neighbour.h>
@@ -40,7 +41,7 @@
 } FIX_ALIASING;
 typedef struct filter_t filter_t;
 
-#define G_filter (*(filter_t*)&bb_common_bufsiz1)
+#define G_filter (*(filter_t*)bb_common_bufsiz1)
 
 static int flush_update(void)
 {
diff --git a/networking/libiproute/iproute.c b/networking/libiproute/iproute.c
index 8282748..34d4f47 100644
--- a/networking/libiproute/iproute.c
+++ b/networking/libiproute/iproute.c
@@ -11,6 +11,7 @@
  */
 
 #include "ip_common.h"  /* #include "libbb.h" is inside */
+#include "common_bufsiz.h"
 #include "rt_names.h"
 #include "utils.h"
 
@@ -43,7 +44,7 @@
 } FIX_ALIASING;
 typedef struct filter_t filter_t;
 
-#define G_filter (*(filter_t*)&bb_common_bufsiz1)
+#define G_filter (*(filter_t*)bb_common_bufsiz1)
 
 static int flush_update(void)
 {