Fix missing libcontainer syscall file

I noticed this file showed up when revendoring dependencies
with vndr.

Also removed `github.com/Microsoft/opengcs` from vendor.conf
as it was not used;

    2017/12/05 22:41:58 WARNING: package github.com/Microsoft/opengcs is unused, consider removing it from vendor.conf

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

vendor.conf

@@ -36,7 +36,6 @@ github.com/BurntSushi/toml v0.2.0-21-g9906417
 github.com/grpc-ecosystem/go-grpc-prometheus 6b7015e65d366bf3f19b2b2a000a831940f0f7e0
 github.com/Microsoft/go-winio v0.4.4
 github.com/Microsoft/hcsshim v0.6.7
-github.com/Microsoft/opengcs v0.3.2
 github.com/boltdb/bolt e9cf4fae01b5a8ff89d0ec6b32f0d9c9f79aefdd
 google.golang.org/genproto d80a6e20e776b0b17a324d0ba1ab50a39c8e8944
 golang.org/x/text 19e51611da83d6be54ddafce4a4af510cb3e9ea4

vendor/github.com/opencontainers/runc/libcontainer/system/syscall_linux_32.go

@@ -0,0 +1,26 @@
+// +build linux
+// +build 386 arm
+
+package system
+
+import (
+	"golang.org/x/sys/unix"
+)
+
+// Setuid sets the uid of the calling thread to the specified uid.
+func Setuid(uid int) (err error) {
+	_, _, e1 := unix.RawSyscall(unix.SYS_SETUID32, uintptr(uid), 0, 0)
+	if e1 != 0 {
+		err = e1
+	}
+	return
+}
+
+// Setgid sets the gid of the calling thread to the specified gid.
+func Setgid(gid int) (err error) {
+	_, _, e1 := unix.RawSyscall(unix.SYS_SETGID32, uintptr(gid), 0, 0)
+	if e1 != 0 {
+		err = e1
+	}
+	return
+}