Fix GLEW debug stuff for Windows

Change-Id: I5fd3df862b59a621af1e3f965abc9820dba08c3f

chart2/source/view/main/DummyXShape.cxx

@@ -1144,8 +1144,12 @@ int oglErrorHandler( Display* /*dpy*/, XErrorEvent* /*evnt*/ )
 
 namespace {
 
-void debug_callback(GLenum source, GLenum type, GLuint id,
-        GLenum severity, GLsizei , const GLchar* message, void* )
+extern "C" void
+#if defined _WIN32
+APIENTRY
+#endif
+debug_callback(GLenum source, GLenum type, GLuint id,
+        GLenum severity, GLsizei , const GLchar* message, GLvoid* )
 {
     SAL_WARN("chart2.opengl", "OpenGL debug message: source: " << source << ", type: "
             << type << ", id: " << id << ", severity: " << severity << " with message: " << message);

chart2/source/view/main/OpenGLRender.hxx

@@ -18,12 +18,7 @@
 #  include "postwin.h"
 #endif
 
-#if defined( MACOSX )
-#  include <GL/glew.h>
-#else
-#  include <GL/gl.h>
-#  include <GL/glu.h>
-#endif
+#include <GL/glew.h>
 
 #include <vcl/window.hxx>
 #include <vcl/syschild.hxx>