lxc: add upstream patch to fix ZFS backing stores

srcpkgs/lxc/patches/fix-rootfs-mount.patch

@@ -0,0 +1,27 @@
+From 26ea5533c941baee14923dfc3edfb9c91666d245 Mon Sep 17 00:00:00 2001
+From: Christian Brauner <christian.brauner@ubuntu.com>
+Date: Mon, 14 Dec 2020 17:52:44 +0100
+Subject: [PATCH] conf: fix block-device based rootfs mounting
+
+Fixes: #3598
+Cc: stable-4.0
+Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
+---
+ src/lxc/conf.c | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+diff --git src/lxc/conf.c src/lxc/conf.c
+index 9f631e0c23..27f9706687 100644
+--- src/lxc/conf.c
++++ src/lxc/conf.c
+@@ -3135,6 +3135,10 @@ int lxc_setup_rootfs_prepare_root(struct lxc_conf *conf, const char *name,
+ 		if (ret < 0)
+ 			return log_error(-1, "Failed to bind mount container / onto itself");
+ 
++		conf->rootfs.mntpt_fd = openat(-EBADF, path, O_RDONLY | O_CLOEXEC | O_DIRECTORY | O_PATH | O_NOCTTY);
++		if (conf->rootfs.mntpt_fd < 0)
++			return log_error_errno(-errno, errno, "Failed to open file descriptor for container rootfs");
++
+ 		return log_trace(0, "Bind mounted container / onto itself");
+ 	}
+ 

srcpkgs/lxc/template

@@ -3,7 +3,7 @@ _desc="Linux Containers"
 
 pkgname=lxc
 version=4.0.5
-revision=1
+revision=2
 build_style=gnu-configure
 configure_args="--enable-doc --enable-seccomp
  --enable-capabilities --enable-apparmor --with-distro=none