testing: Add wrapper for systemctl to collect leaks from charon-systemd

Similar to the wrapper around `service` added with 71d59af58a, this
sets the variable only when running the automated tests.

testing/hosts/default/usr/local/bin/systemctl

@@ -0,0 +1,22 @@
+#!/bin/bash
+#
+# LEAK_DETECTIVE_LOG is set for automated runs, however, this is not passed
+# to a process started via systemctl. This wrapper is used to set the variable
+# for the strongswan-swanctl.service unit.
+
+ORIG=/bin/systemctl
+CONF=/lib/systemd/system/strongswan-swanctl.service
+
+if [[ "$2" != "strongswan-swanctl" ]]; then
+	$ORIG "$@"
+fi
+
+if [[ "$1" == "start" && -n $LEAK_DETECTIVE_LOG ]]; then
+	sed -i "s:Type=:Environment=LEAK_DETECTIVE_LOG=$LEAK_DETECTIVE_LOG\nType=:" $CONF 2>/dev/null
+fi
+
+$ORIG "$@"
+
+if [[ "$1" == "stop" ]]; then
+	sed -i '/LEAK_DETECTIVE_LOG/d' $CONF 2>/dev/null
+fi