configure: include glew.h before wglew.h

In recent wglew.h it relies on the DLL export mode defined in glew.h

configure.ac

@@ -3436,12 +3436,15 @@ AS_IF([test "${enable_directx}" != "no"], [
   ])
 
   dnl OpenGL
-  AC_CHECK_HEADERS([GL/wglew.h], [
-    VLC_ADD_PLUGIN([glwin32 wgl])
-  ],, [
-    #include <windows.h>
-    #include <GL/gl.h>
-  ])
+  AC_CHECK_HEADERS([GL/glew.h], [
+    AC_CHECK_HEADERS([GL/wglew.h], [
+        VLC_ADD_PLUGIN([glwin32 wgl])
+      ],, [
+        #include <windows.h>
+        #include <GL/glew.h>
+      ])],, [
+      #include <windows.h>
+   ])
 
   dnl Direct3D11
   AC_CHECK_HEADERS([d3d11.h], [

modules/video_output/opengl/converter.h

@@ -45,7 +45,7 @@
 #  include <GLES2/gl2.h>
 #  include <GLES2/gl2ext.h>
 # else
-#  ifdef _WIN32
+#  ifdef HAVE_GL_WGLEW_H
 #   include <GL/glew.h>
 #  endif
 #  include <GL/gl.h>

modules/video_output/win32/direct3d9.c

@@ -1747,8 +1747,9 @@ static void Close(vout_display_t *vd)
     free(vd->sys);
 }
 
-#ifdef HAVE_GL
+#if defined(HAVE_GL) && defined(HAVE_GL_WGLEW_H)
 #include "../opengl/converter.h"
+#include <GL/glew.h>
 #include <GL/wglew.h>
 
 struct wgl_vt {

modules/video_output/win32/wgl.c

@@ -29,6 +29,7 @@
 #include <vlc_opengl.h>
 
 #include "../opengl/vout_helper.h"
+#include <GL/glew.h>
 #include <GL/wglew.h>
 
 #include "common.h"