unix: update Dockerfile to Linux 5.2 and Go 1.13beta1

Change-Id: I1a63f6ae5fe6b8b6fb4f493837b12dbe3c2860d4
Reviewed-on: https://go-review.googlesource.com/c/sys/+/185497
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/unix/zsysnum_linux_386.go b/unix/zsysnum_linux_386.go
index 33b6e4d..e869c06 100644
--- a/unix/zsysnum_linux_386.go
+++ b/unix/zsysnum_linux_386.go
@@ -423,4 +423,10 @@
 	SYS_IO_URING_SETUP               = 425
 	SYS_IO_URING_ENTER               = 426
 	SYS_IO_URING_REGISTER            = 427
+	SYS_OPEN_TREE                    = 428
+	SYS_MOVE_MOUNT                   = 429
+	SYS_FSOPEN                       = 430
+	SYS_FSCONFIG                     = 431
+	SYS_FSMOUNT                      = 432
+	SYS_FSPICK                       = 433
 )