[skel/installer] Add /usr/bin/groups to installer skeleton, fixes xc-279

diff --git a/target/generic/target_xenclient_installer_skeleton/usr/bin/groups b/target/generic/target_xenclient_installer_skeleton/usr/bin/groups
new file mode 100755 (executable)
index 0000000..a60a063
--- /dev/null
+++ b/target/generic/target_xenclient_installer_skeleton/usr/bin/groups
@@ -0,0 +1,3 @@
+#!/bin/sh
+
+id -Gn