vfs: cleaned up tcp_init()

tcp_init() is now called by every vfs which needs it and prevents
itself from duplicate initialization.

this is the first step to get rid of --enable-netcode and so clean
up things a bit.

vfs/fish.c

@@ -1233,6 +1233,8 @@ init_fish (void)
 {
     static struct vfs_s_subclass fish_subclass;
 
+    tcp_init();
+
     fish_subclass.flags = VFS_S_REMOTE;
     fish_subclass.archive_same = fish_archive_same;
     fish_subclass.open_archive = fish_open_archive;

vfs/ftpfs.c

@@ -2141,6 +2141,8 @@ init_ftpfs (void)
 {
     static struct vfs_s_subclass ftpfs_subclass;
 
+    tcp_init();
+
     ftpfs_subclass.flags = VFS_S_REMOTE;
     ftpfs_subclass.archive_same = ftpfs_archive_same;
     ftpfs_subclass.open_archive = ftpfs_open_archive;

vfs/mcfs.c

@@ -1186,6 +1186,8 @@ mcfs_setctl (struct vfs_class *me, const char *path, int ctlop, void *arg)
 void
 init_mcfs (void)
 {
+    tcp_init();
+
     vfs_mcfs_ops.name = "mcfs";
     vfs_mcfs_ops.prefix = "mc:";
     vfs_mcfs_ops.fill_names = mcfs_fill_names;

vfs/netutil.c

@@ -43,10 +43,16 @@ void
 tcp_init (void)
 {
     struct sigaction sa;
+    static char _initialized = 0;
+
+    if (_initialized)
+	return;
 
     got_sigpipe = 0;
     sa.sa_handler = sig_pipe;
     sa.sa_flags = 0;
     sigemptyset (&sa.sa_mask);
     sigaction (SIGPIPE, &sa, NULL);
+
+    _initialized = 1;
 }

vfs/smbfs.c

@@ -65,6 +65,7 @@
 #include "vfs.h"
 #include "vfs-impl.h"
 #include "smbfs.h"
+#include "vfs/netutil.h"
 
 #define SMBFS_MAX_CONNECTIONS 16
 static const char * const IPC = "IPC$";
@@ -1967,6 +1968,8 @@ smbfs_fstat (void *data, struct stat *buf)
 void
 init_smbfs (void)
 {
+    tcp_init();
+
     vfs_smbfs_ops.name = "smbfs";
     vfs_smbfs_ops.prefix = "smb:";
     vfs_smbfs_ops.flags = VFSF_NOLINKS;

vfs/vfs.c

@@ -1279,7 +1279,6 @@ vfs_init (void)
 #endif /* USE_EXT2FSLIB */
 
 #ifdef USE_NETCODE
-    tcp_init();
     init_ftpfs ();
     init_fish ();
 #ifdef ENABLE_VFS_SMB