net.h/skbuff.h: Remove extern from function prototypes

There are a mix of function prototypes with and without extern
in the kernel sources.  Standardize on not using extern for
function prototypes.

Function prototypes don't need to be written with extern.
extern is assumed by the compiler.  Its use is as unnecessary as
using auto to declare automatic/local variables in a block.
Signed-off-by: Joe Perches <joe@perches.com>

include/linux/net.h

@@ -195,27 +195,23 @@ enum {
 	SOCK_WAKE_URG,
 };
 
-extern int	     sock_wake_async(struct socket *sk, int how, int band);
-extern int	     sock_register(const struct net_proto_family *fam);
-extern void	     sock_unregister(int family);
-extern int	     __sock_create(struct net *net, int family, int type, int proto,
-				 struct socket **res, int kern);
-extern int	     sock_create(int family, int type, int proto,
-				 struct socket **res);
-extern int	     sock_create_kern(int family, int type, int proto,
-				      struct socket **res);
-extern int	     sock_create_lite(int family, int type, int proto,
-				      struct socket **res); 
-extern void	     sock_release(struct socket *sock);
-extern int   	     sock_sendmsg(struct socket *sock, struct msghdr *msg,
-				  size_t len);
-extern int	     sock_recvmsg(struct socket *sock, struct msghdr *msg,
-				  size_t size, int flags);
-extern struct file  *sock_alloc_file(struct socket *sock, int flags, const char *dname);
-extern struct socket *sockfd_lookup(int fd, int *err);
-extern struct socket *sock_from_file(struct file *file, int *err);
+int sock_wake_async(struct socket *sk, int how, int band);
+int sock_register(const struct net_proto_family *fam);
+void sock_unregister(int family);
+int __sock_create(struct net *net, int family, int type, int proto,
+		  struct socket **res, int kern);
+int sock_create(int family, int type, int proto, struct socket **res);
+int sock_create_kern(int family, int type, int proto, struct socket **res);
+int sock_create_lite(int family, int type, int proto, struct socket **res);
+void sock_release(struct socket *sock);
+int sock_sendmsg(struct socket *sock, struct msghdr *msg, size_t len);
+int sock_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
+		 int flags);
+struct file *sock_alloc_file(struct socket *sock, int flags, const char *dname);
+struct socket *sockfd_lookup(int fd, int *err);
+struct socket *sock_from_file(struct file *file, int *err);
 #define		     sockfd_put(sock) fput(sock->file)
-extern int	     net_ratelimit(void);
+int net_ratelimit(void);
 
 #define net_ratelimited_function(function, ...)			\
 do {								\
@@ -243,32 +239,28 @@ do {								\
 #define net_random()		prandom_u32()
 #define net_srandom(seed)	prandom_seed((__force u32)(seed))
 
-extern int   	     kernel_sendmsg(struct socket *sock, struct msghdr *msg,
-				    struct kvec *vec, size_t num, size_t len);
-extern int   	     kernel_recvmsg(struct socket *sock, struct msghdr *msg,
-				    struct kvec *vec, size_t num,
-				    size_t len, int flags);
+int kernel_sendmsg(struct socket *sock, struct msghdr *msg, struct kvec *vec,
+		   size_t num, size_t len);
+int kernel_recvmsg(struct socket *sock, struct msghdr *msg, struct kvec *vec,
+		   size_t num, size_t len, int flags);
 
-extern int kernel_bind(struct socket *sock, struct sockaddr *addr,
-		       int addrlen);
-extern int kernel_listen(struct socket *sock, int backlog);
-extern int kernel_accept(struct socket *sock, struct socket **newsock,
-			 int flags);
-extern int kernel_connect(struct socket *sock, struct sockaddr *addr,
-			  int addrlen, int flags);
-extern int kernel_getsockname(struct socket *sock, struct sockaddr *addr,
-			      int *addrlen);
-extern int kernel_getpeername(struct socket *sock, struct sockaddr *addr,
-			      int *addrlen);
-extern int kernel_getsockopt(struct socket *sock, int level, int optname,
-			     char *optval, int *optlen);
-extern int kernel_setsockopt(struct socket *sock, int level, int optname,
-			     char *optval, unsigned int optlen);
-extern int kernel_sendpage(struct socket *sock, struct page *page, int offset,
-			   size_t size, int flags);
-extern int kernel_sock_ioctl(struct socket *sock, int cmd, unsigned long arg);
-extern int kernel_sock_shutdown(struct socket *sock,
-				enum sock_shutdown_cmd how);
+int kernel_bind(struct socket *sock, struct sockaddr *addr, int addrlen);
+int kernel_listen(struct socket *sock, int backlog);
+int kernel_accept(struct socket *sock, struct socket **newsock, int flags);
+int kernel_connect(struct socket *sock, struct sockaddr *addr, int addrlen,
+		   int flags);
+int kernel_getsockname(struct socket *sock, struct sockaddr *addr,
+		       int *addrlen);
+int kernel_getpeername(struct socket *sock, struct sockaddr *addr,
+		       int *addrlen);
+int kernel_getsockopt(struct socket *sock, int level, int optname, char *optval,
+		      int *optlen);
+int kernel_setsockopt(struct socket *sock, int level, int optname, char *optval,
+		      unsigned int optlen);
+int kernel_sendpage(struct socket *sock, struct page *page, int offset,
+		    size_t size, int flags);
+int kernel_sock_ioctl(struct socket *sock, int cmd, unsigned long arg);
+int kernel_sock_shutdown(struct socket *sock, enum sock_shutdown_cmd how);
 
 #define MODULE_ALIAS_NETPROTO(proto) \
 	MODULE_ALIAS("net-pf-" __stringify(proto))