fix compile error on OSX

git-svn-id: http://svn.osgeo.org/qgis/trunk@10256 c8812cc2-4d05-0410-92ff-de0c093fc19c

Author: jef

src/plugins/interpolation/qgsinterpolator.cpp

@@ -18,7 +18,11 @@
 #include "qgsinterpolator.h"
 #include "qgsvectordataprovider.h"
 #include "qgsgeometry.h"
+#ifndef Q_OS_MACX
 #include <cmath>
+#else
+#include <math.h>
+#endif
 #ifdef _MSC_VER
 #include <float.h>
 #define isnan(f) _isnan(f)