Add -std=c++11 for basic in Makefile

Makefile

@@ -4,7 +4,7 @@ minimal: examples/minimal.cpp matplotlibcpp.h
 	cd examples && g++ -DWITHOUT_NUMPY minimal.cpp -I/usr/include/python2.7 -lpython2.7 -o minimal -std=c++11
 
 basic: examples/basic.cpp matplotlibcpp.h
-	cd examples && g++ basic.cpp -I/usr/include/python2.7 -lpython2.7 -o basic
+	cd examples && g++ basic.cpp -I/usr/include/python2.7 -lpython2.7 -o basic -std=c++11
 
 modern: examples/modern.cpp matplotlibcpp.h
 	cd examples && g++ modern.cpp -I/usr/include/python2.7 -lpython2.7 -o modern -std=c++11