Add buildflags to allow crosscompilation for apparmor

Docker-DCO-1.1-Signed-off-by: Guillaume J. Charmes <guillaume.charmes@docker.com> (github: creack)

pkg/libcontainer/apparmor/apparmor.go

@@ -1,3 +1,5 @@
+// +build apparmor
+
 package apparmor
 
 // #cgo LDFLAGS: -lapparmor

pkg/libcontainer/apparmor/apparmor_disabled.go

@@ -0,0 +1,13 @@
+// +build !apparmor
+
+package apparmor
+
+import ()
+
+func IsEnabled() bool {
+	return false
+}
+
+func ApplyProfile(pid int, name string) error {
+	return nil
+}