Switch to C++14

Change-Id: I5c9d7ab7038a911d7432d511a820b86e4aebfc22
Refs: #3076
diff --git a/install_helpers/tools/Makefile b/install_helpers/tools/Makefile
index dd395bd..62def39 100644
--- a/install_helpers/tools/Makefile
+++ b/install_helpers/tools/Makefile
@@ -1,5 +1,5 @@
 CXX = g++
-CXXFLAGS = -std=c++11 -Wall -Werror `pkg-config --cflags libndn-cxx`
+CXXFLAGS = -std=c++14 -Wall -Werror `pkg-config --cflags libndn-cxx`
 LIBS = `pkg-config --libs libndn-cxx`
 DESTDIR ?= /usr/local