[patch] net, 9p: build fix with !CONFIG_SYSCTL

[Ingo Molnar <mingo@elte.hu>]

Subject: net, 9p: build fix with !CONFIG_SYSCTL
From: Ingo Molnar <mingo@elte.hu>

found via make randconfig build testing: 

 net/built-in.o: In function `init_p9':
 mod.c:(.init.text+0x3b39): undefined reference to `p9_sysctl_register'
 net/built-in.o: In function `exit_p9':
 mod.c:(.exit.text+0x36b): undefined reference to `p9_sysctl_unregister'

Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 include/net/9p/9p.h |   12 ++++++++++++
 1 file changed, 12 insertions(+)

Index: linux/include/net/9p/9p.h
===================================================================
--- linux.orig/include/net/9p/9p.h
+++ linux/include/net/9p/9p.h
@@ -412,6 +412,18 @@ int p9_idpool_check(int id, struct p9_id
 
 int p9_error_init(void);
 int p9_errstr2errno(char *, int);
+
+#ifdef CONFIG_SYSCTL
 int __init p9_sysctl_register(void);
 void __exit p9_sysctl_unregister(void);
+#else
+static inline int p9_sysctl_register(void)
+{
+	return 0;
+}
+static inline void p9_sysctl_unregister(void)
+{
+}
+#endif
+
 #endif /* NET_9P_H */