Add missing "proto2" syntax marker

.. to address protobuf 3.x proto-c warnings
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

images/binfmt-misc.proto

+syntax = "proto2";
+
 message binfmt_misc_entry {
 	required string		name			= 1;
 	required bool		enabled			= 2;

images/cgroup.proto

+syntax = "proto2";
+
 message cgroup_perms {
 	required uint32			mode		= 1;
 	required uint32			uid		= 2;

images/core-aarch64.proto

+syntax = "proto2";
+
 message user_aarch64_regs_entry {
 	repeated uint64 regs	= 1;
 	required uint64 sp	= 2;

images/core-arm.proto

+syntax = "proto2";
+
 message user_arm_regs_entry {
 	required uint32 r0      = 1;
 	required uint32 r1      = 2;

images/core-ppc64.proto

+syntax = "proto2";
+
 message user_ppc64_regs_entry {
 	// Following is the list of regiters starting at r0.
 	repeated uint64 gpr		= 1;

images/core-x86.proto

+syntax = "proto2";
+
 import "opts.proto";
 
 message user_x86_regs_entry {

images/core.proto

+syntax = "proto2";
+
 import "core-x86.proto";
 import "core-arm.proto";
 import "core-aarch64.proto";

images/cpuinfo.proto

+syntax = "proto2";
+
 message cpuinfo_x86_entry {
 	enum vendor {
 		UNKNOWN		= 0;

images/creds.proto

+syntax = "proto2";
+
 message creds_entry {
 	required uint32 uid	= 1;
 	required uint32	gid	= 2;

images/eventfd.proto

+syntax = "proto2";
+
 import "fown.proto";
 
 message eventfd_file_entry {

images/eventpoll.proto

+syntax = "proto2";
+
 import "fown.proto";
 
 message eventpoll_tfd_entry {

images/ext-file.proto

+syntax = "proto2";
+
 import "fown.proto";
 
 message ext_file_entry {

images/fdinfo.proto

+syntax = "proto2";
+
 enum fd_types {
 	UND		= 0;
 	REG		= 1;

images/fh.proto

+syntax = "proto2";
+
 import "opts.proto";
 
 enum fh_entry_sizes {

images/fifo.proto

+syntax = "proto2";
+
 message fifo_entry {
 	required uint32		id		= 1;
 	required uint32		pipe_id		= 2;

images/file-lock.proto

+syntax = "proto2";
+
 message file_lock_entry {
     required uint32	flag  = 1;
     required uint32	type  = 2;

images/fown.proto

+syntax = "proto2";
+
 message fown_entry {
 	required uint32		uid		= 1;
 	required uint32		euid		= 2;

images/fs.proto

+syntax = "proto2";
+
 message fs_entry {
 	required uint32		cwd_id		= 1;
 	required uint32		root_id		= 2;

images/fsnotify.proto

+syntax = "proto2";
+
 import "opts.proto";
 import "fh.proto";
 import "fown.proto";

images/ghost-file.proto

+syntax = "proto2";
+
 import "opts.proto";
 import "time.proto";
 

images/inventory.proto

+syntax = "proto2";
+
 import "core.proto";
 
 enum lsmtype {

images/ipc-desc.proto

+syntax = "proto2";
+
 message ipc_desc_entry {
 	required uint32		key	= 1;
 	required uint32		uid	= 2;

images/ipc-msg.proto

+syntax = "proto2";
+
 import "ipc-desc.proto";
 
 message ipc_msg {

images/ipc-sem.proto

+syntax = "proto2";
+
 import "ipc-desc.proto";
 
 message ipc_sem_entry {

images/ipc-shm.proto

+syntax = "proto2";
+
 import "ipc-desc.proto";
 
 message ipc_shm_entry {

images/ipc-var.proto

+syntax = "proto2";
+
 message ipc_var_entry {
 	repeated uint32			sem_ctls		=  1;
 	required uint32			msg_ctlmax		=  2;

images/mm.proto

+syntax = "proto2";
+
 import "opts.proto";
 import "vma.proto";
 

images/mnt.proto

+syntax = "proto2";
+
 import "opts.proto";
 
 enum fstype {

images/netdev.proto

+syntax = "proto2";
+
 import "opts.proto";
 import "tun.proto";
 import "sysctl.proto";

images/ns.proto

+syntax = "proto2";
+
 message ns_file_entry {
 	required uint32		id		= 1;
 	required uint32		ns_id		= 2;

images/opts.proto

+syntax = "proto2";
+
 import "google/protobuf/descriptor.proto";
 
 message CRIU_Opts {

images/packet-sock.proto

+syntax = "proto2";
+
 import "opts.proto";
 import "fown.proto";
 import "sk-opts.proto";

images/pagemap.proto

+syntax = "proto2";
+
 import "opts.proto";
 
 message pagemap_head {

images/pipe-data.proto

+syntax = "proto2";
+
 message pipe_data_entry {
 	required uint32	pipe_id		= 1;
 	required uint32	bytes		= 2;

images/pipe.proto

+syntax = "proto2";
+
 import "opts.proto";
 import "fown.proto";
 

images/pstree.proto

+syntax = "proto2";
+
 message pstree_entry {
 	required uint32			pid		= 1;
 	required uint32			ppid		= 2;

images/regfile.proto

+syntax = "proto2";
+
 import "opts.proto";
 import "fown.proto";
 

images/remap-file-path.proto

+syntax = "proto2";
+
 enum remap_type {
   LINKED		= 0;
   GHOST 		= 1;

images/rlimit.proto

+syntax = "proto2";
+
 message rlimit_entry {
 	required uint64		cur = 1;
 	required uint64		max = 2;

images/rpc.proto

+syntax = "proto2";
+
 message criu_page_server_info {
 	optional string		address	= 1;
 	optional int32		port	= 2;

images/sa.proto

+syntax = "proto2";
+
 import "opts.proto";
 
 message sa_entry {

images/seccomp.proto

+syntax = "proto2";
+
 message seccomp_filter {
 	required bytes		filter			= 1;
 	optional uint32		prev			= 2;

images/siginfo.proto

+syntax = "proto2";
+
 message siginfo_entry {
 	required bytes siginfo = 1;
 }

images/signalfd.proto

+syntax = "proto2";
+
 import "opts.proto";
 import "fown.proto";
 

images/sk-inet.proto

+syntax = "proto2";
+
 import "opts.proto";
 import "fown.proto";
 import "sk-opts.proto";

images/sk-netlink.proto

+syntax = "proto2";
+
 import "opts.proto";
 import "fown.proto";
 import "sk-opts.proto";

images/sk-opts.proto

+syntax = "proto2";
+
 message sk_opts_entry {
 	required uint32		so_sndbuf	= 1;
 	required uint32		so_rcvbuf	= 2;

images/sk-packet.proto

+syntax = "proto2";
+
 message sk_packet_entry {
 	required uint32		id_for		= 1;
 	required uint32		length		= 2;

images/sk-unix.proto

+syntax = "proto2";
+
 import "opts.proto";
 import "fown.proto";
 import "sk-opts.proto";

images/stats.proto

+syntax = "proto2";
+
 // This one contains statistics about dump/restore process
 message dump_stats_entry {
 	required uint32			freezing_time		= 1;

images/sysctl.proto

+syntax = "proto2";
+
 enum SysctlType {
 	CTL_STR	= 5;
 	CTL_32	= 6;

images/tcp-stream.proto

+syntax = "proto2";
+
 import "opts.proto";
 
 message tcp_stream_entry {

images/time.proto

+syntax = "proto2";
+
 message timeval {
 	required uint64		tv_sec	= 1;
 	required uint64		tv_usec	= 2;

images/timer.proto

+syntax = "proto2";
+
 message itimer_entry {
 	required uint64		isec		= 1;
 	required uint64		iusec		= 2;

images/timerfd.proto

+syntax = "proto2";
+
 import "opts.proto";
 import "fown.proto";
 

images/tty.proto

+syntax = "proto2";
+
 import "opts.proto";
 import "fown.proto";
 

images/tun.proto

+syntax = "proto2";
+
 import "opts.proto";
 
 message tunfile_entry {

images/userns.proto

+syntax = "proto2";
+
 message uid_gid_extent {
 	required uint32 first		= 1;
 	required uint32 lower_first	= 2;

images/utsns.proto

+syntax = "proto2";
+
 message utsns_entry {
 	required string nodename	= 1;
 	required string domainname	= 2;

images/vma.proto

+syntax = "proto2";
+
 import "opts.proto";
 
 message vma_entry {

test/others/unix-callback/unix.proto

+syntax = "proto2";
+
 message unix_test {
 	required uint32 val = 1;
 	required bytes name = 2;

test/zdtm/static/criu-rtc.proto

+syntax = "proto2";
+
 message criu_rtc {
 	required uint64	IRQP = 1;
 }