networking/interface.c: reduce bss usage

function                                             old     new   delta
.rodata                                           158918  158950     +32
display_interfaces                                   133     153     +20
UNSPEC_print                                          56      68     +12
pr_ether                                              59      65      +6
static.proc_read                                       4       1      -3
interface_opt_a                                        4       1      -3
in_ether                                             139     136      -3
ifconfig_main                                       1296    1293      -3
if_readlist_proc                                     686     680      -6
ife_print                                           1350    1338     -12
do_if_print                                           46       -     -46
static.buff                                          369     264    -105
------------------------------------------------------------------------------
(add/remove: 0/1 grow/shrink: 4/7 up/down: 70/-181)          Total: -111 bytes

# size busybox_old busybox_unstripped
   text    data     bss     dec     hex filename
 751073    3080   14800  768953   bbbb9 busybox_old
 751073    3048   14688  768809   bbb29 busybox_unstripped

2 files changed, 7 insertions, 6 deletions

diff --git a/include/inet_common.h b/include/inet_common.h
index bda621198..fa48fdffa 100644
--- a/include/inet_common.h
+++ b/include/inet_common.h
@@ -12,14 +12,15 @@
 /* hostfirst!=0 If we expect this to be a hostname,
    try hostname database first
  */
-extern int INET_resolve(const char *name, struct sockaddr_in *s_in, int hostfirst);
+int INET_resolve(const char *name, struct sockaddr_in *s_in, int hostfirst);
 
 /* numeric: & 0x8000: "default" instead of "*",
  *          & 0x4000: host instead of net,
  *          & 0x0fff: don't resolve
  */
-extern int INET_rresolve(char *name, size_t len, struct sockaddr_in *s_in,
-                         int numeric, unsigned int netmask);
+int INET_rresolve(char *name, size_t len, struct sockaddr_in *s_in,
+        int numeric, unsigned int netmask);
 
-extern int INET6_resolve(const char *name, struct sockaddr_in6 *sin6);
-extern int INET6_rresolve(char *name, size_t len, struct sockaddr_in6 *sin6, int numeric);
+
+int INET6_resolve(const char *name, struct sockaddr_in6 *sin6);
+int INET6_rresolve(char *name, size_t len, struct sockaddr_in6 *sin6, int numeric);
diff --git a/include/libbb.h b/include/libbb.h
index 3c9f9fe81..999caae0c 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -699,7 +699,7 @@ struct hwtype {
         int (*activate) (int fd);
         int suppress_null_addr;
 };
-extern int interface_opt_a;
+extern smallint interface_opt_a;
 int display_interfaces(char *ifname);
 const struct aftype *get_aftype(const char *name);
 const struct hwtype *get_hwtype(const char *name);