[NET]: prot_inuse cleanups and optimizations

1) Cleanups (all functions are prefixed by sock_prot_inuse)

sock_prot_inc_use(prot) -> sock_prot_inuse_add(prot,-1)
sock_prot_dec_use(prot) -> sock_prot_inuse_add(prot,-1)
sock_prot_inuse()       -> sock_prot_inuse_get()

New functions :

sock_prot_inuse_init() and sock_prot_inuse_free() to abstract pcounter use.

2) if CONFIG_PROC_FS=n, we can zap 'inuse' member from "struct proto",
since nobody wants to read the inuse value.

This saves 1372 bytes on i386/SMP and some cpu cycles.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/proc.c b/net/ipv6/proc.c
index 41e9980..571d95a 100644
--- a/net/ipv6/proc.c
+++ b/net/ipv6/proc.c
@@ -36,13 +36,13 @@
 static int sockstat6_seq_show(struct seq_file *seq, void *v)
 {
 	seq_printf(seq, "TCP6: inuse %d\n",
-		       sock_prot_inuse(&tcpv6_prot));
+		       sock_prot_inuse_get(&tcpv6_prot));
 	seq_printf(seq, "UDP6: inuse %d\n",
-		       sock_prot_inuse(&udpv6_prot));
+		       sock_prot_inuse_get(&udpv6_prot));
 	seq_printf(seq, "UDPLITE6: inuse %d\n",
-			sock_prot_inuse(&udplitev6_prot));
+			sock_prot_inuse_get(&udplitev6_prot));
 	seq_printf(seq, "RAW6: inuse %d\n",
-		       sock_prot_inuse(&rawv6_prot));
+		       sock_prot_inuse_get(&rawv6_prot));
 	seq_printf(seq, "FRAG6: inuse %d memory %d\n",
 		       ip6_frag_nqueues(), ip6_frag_mem());
 	return 0;