Fix building with C++14, which errors out due to collisions with isinf
from cmath. We don't need to fix ancient broken OSX toolchains.
See also: https://bugs.gentoo.org/show_bug.cgi?id=594700

--- a/src/SensorPlugins/Tester/Sensor.Tester.cc
+++ b/src/SensorPlugins/Tester/Sensor.Tester.cc
@@ -18,9 +18,7 @@
 // ------------------------------------------------------------------
 
 // MacOS-X kludge. cmath undefines these macros. Turn them into inlines 
-#include <math.h>
-inline int (isinf)(double r) { return isinf(r); }
-inline int (isnan)(double r) { return isnan(r); }
+#include <cmath>
 
 #include <iomanip>
 #include <fstream>