Prevent NOMINMAX warnings

src/libslic3r/OpenVDBUtils.cpp

@@ -1,4 +1,3 @@
-#define NOMINMAX
 #include "OpenVDBUtils.hpp"
 
 #ifdef _MSC_VER

src/libslic3r/SLA/SupportTreeBuilder.cpp

@@ -1,9 +1,6 @@
-#define NOMINMAX
-
 #include <libslic3r/SLA/SupportTreeBuilder.hpp>
 #include <libslic3r/SLA/SupportTreeUtils.hpp>
 #include <libslic3r/SLA/SupportTreeMesher.hpp>
-//#include <libslic3r/SLA/Contour3D.hpp>
 
 namespace Slic3r {
 namespace sla {

src/slic3r/GUI/GUI.cpp

@@ -16,7 +16,9 @@
 #import <IOKit/pwr_mgt/IOPMLib.h>
 #elif _WIN32
 #define WIN32_LEAN_AND_MEAN
-#define NOMINMAX
+#ifndef NOMINMAX
+    #define NOMINMAX
+#endif
 #include <Windows.h>
 #include "boost/nowide/convert.hpp"
 #endif

src/slic3r/GUI/SysInfoDialog.cpp

@@ -23,7 +23,9 @@
 #ifdef _WIN32
 	// The standard Windows includes.
 	#define WIN32_LEAN_AND_MEAN
+#ifndef NOMINMAX
 	#define NOMINMAX
+#endif
 	#include <Windows.h>
 	#include <psapi.h>
 #endif /* _WIN32 */