Fix build with OpenEXR>=3: error: use of undeclared identifier 'DBL_MAX'

Index: src/render/PointArray.cpp
--- src/render/PointArray.cpp.orig
+++ src/render/PointArray.cpp
@@ -7,6 +7,8 @@
 
 #include "glutil.h"
 
+#include <float.h>
+
 #include <QGLShaderProgram>
 #include <QTime>
 
