buildmod => buildmode

There was a typo with the buildmode flag for containerd

Signed-off-by: Eli Uriegas <eli.uriegas@docker.com>
(cherry picked from commit 5e4885b9afb1de30133627ce751af2c0e7b72a4e)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
diff --git a/hack/dockerfile/install/containerd.installer b/hack/dockerfile/install/containerd.installer
index 1b42a48..d6ab837 100755
--- a/hack/dockerfile/install/containerd.installer
+++ b/hack/dockerfile/install/containerd.installer
@@ -15,7 +15,7 @@
 	(
 
 		export BUILDTAGS='static_build netgo'
-		export EXTRA_FLAGS='-buildmod pie'
+		export EXTRA_FLAGS='-buildmode=pie'
 		export EXTRA_LDFLAGS='-extldflags "-fno-PIC -static"'
 
 		# Reset build flags to nothing if we want a dynbinary