tests+tools: fix build with clang-5.0

Change-Id: I75eeb01b071c1702517a65a8099e52d4092a4638
Refs: #4278
diff --git a/tests/daemon/mgmt/face-manager-update-face.t.cpp b/tests/daemon/mgmt/face-manager-update-face.t.cpp
index 1d647fc..9a6825e 100644
--- a/tests/daemon/mgmt/face-manager-update-face.t.cpp
+++ b/tests/daemon/mgmt/face-manager-update-face.t.cpp
@@ -124,7 +124,7 @@
 
     bool hasCallbackFired = false;
     signal::ScopedConnection connection = this->node1.face.onSendData.connect(
-      [this, req, &hasCallbackFired, &checkResp] (const Data& response) {
+      [req, &hasCallbackFired, &checkResp] (const Data& response) {
         if (!req.getName().isPrefixOf(response.getName())) {
           return;
         }