general: Fix missing includes on Windows.

panda/src/wgldisplay/wglGraphicsBuffer.cxx

@@ -16,6 +16,7 @@
 #include "wglGraphicsPipe.h"
 #include "config_wgldisplay.h"
 #include "glgsg.h"
+#include "wglGraphicsStateGuardian.h"
 #include "pStatTimer.h"
 
 #include <wingdi.h>

panda/src/wgldisplay/wglGraphicsPipe.cxx

@@ -17,6 +17,7 @@
 #include "config_windisplay.h"
 #include "wglGraphicsWindow.h"
 #include "wglGraphicsBuffer.h"
+#include "wglGraphicsStateGuardian.h"
 
 typedef enum {Software, MCD, ICD} OGLDriverType;
 

panda/src/wgldisplay/wglGraphicsStateGuardian.cxx

@@ -13,7 +13,9 @@
 ////////////////////////////////////////////////////////////////////
 
 #include "wglGraphicsStateGuardian.h"
+#include "config_wgldisplay.h"
 #include "wglGraphicsBuffer.h"
+#include "wglGraphicsPipe.h"
 #include "string_utils.h"
 
 TypeHandle wglGraphicsStateGuardian::_type_handle;

panda/src/wgldisplay/wglGraphicsWindow.cxx

@@ -18,6 +18,7 @@
 #include "wglGraphicsPipe.h"
 #include "pStatTimer.h"
 #include "glgsg.h"
+#include "wglGraphicsStateGuardian.h"
 
 #include <wingdi.h>