Update containerd to v1.2.1-rc.0

The previous update used a commit from master. Now that
all the fixes are backported to the containerd 1.2 release
branch, we can switch back to that branch.

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

Author: thaJeztah

hack/dockerfile/install/containerd.installer

@@ -4,7 +4,7 @@
 # containerd is also pinned in vendor.conf. When updating the binary
 # version you may also need to update the vendor version to pick up bug
 # fixes or new APIs.
-CONTAINERD_COMMIT=aa537a67b3a9026c423a63dbaf71e4cc0776b2ad # v1.2.0-13-g8afcade1
+CONTAINERD_COMMIT=de1f167ab96338a9f5c2b17347abf84bdf1dd411 # v1.2.1-rc.0
 
 install_containerd() {
 	echo "Install containerd version $CONTAINERD_COMMIT"

vendor.conf

@@ -118,7 +118,7 @@ github.com/googleapis/gax-go v2.0.0
 google.golang.org/genproto 694d95ba50e67b2e363f3483057db5d4910c18f9
 
 # containerd
-github.com/containerd/containerd aa537a67b3a9026c423a63dbaf71e4cc0776b2ad # v1.2.0
+github.com/containerd/containerd de1f167ab96338a9f5c2b17347abf84bdf1dd411 # v1.2.1-rc.0
 github.com/containerd/fifo 3d5202aec260678c48179c56f40e6f38a095738c
 github.com/containerd/continuity bd77b46c8352f74eb12c85bdc01f4b90f69d66b4
 github.com/containerd/cgroups 5e610833b72089b37d0e615de9a92dfc043757c2