tcp: Prepare sk-inet for dumping and restoring tcp connections

First of all -- to make crtools dump/restore established tcp sockets
you have to specify the --tcp-established options. By doing so you
inform crtools that

a) you know, that after dump there will be a netfilter rules blocking
   the dumped connections

b) you guarantee, that before restore this netfilter block is still
   there

What else this patch does is simple -- collects establised sockets and
calls the dump/restore tcp function (now empty) where appropriate.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

crtools.c

@@ -22,6 +22,8 @@
 #include "syscall.h"
 #include "uts_ns.h"
 #include "ipc_ns.h"
+#include "files.h"
+#include "sk-inet.h"
 
 struct cr_options opts;
 
@@ -347,6 +349,7 @@ int main(int argc, char *argv[])
 			{ "namespaces", required_argument, 0, 'n' },
 			{ "ext-unix-sk", no_argument, 0, 'x' },
 			{ "help", no_argument, 0, 'h' },
+			{ SK_EST_PARAM, no_argument, 0, 42 },
 			{ },
 		};
 
@@ -410,6 +413,10 @@ int main(int argc, char *argv[])
 					log_level++;
 			}
 			break;
+		case 42:
+			pr_info("Will dump TCP connections\n");
+			opts.tcp_established_ok = true;
+			break;
 		case 'h':
 		default:
 			goto usage;