Implemented vlc_gl_t::getProcAddress() for glwin32.

modules/video_output/msw/glwin32.c

@@ -67,6 +67,7 @@ static int            Control(vout_display_t *, int, va_list);
 static void           Manage (vout_display_t *);
 
 static void           Swap   (vlc_gl_t *);
+static void          *GetProcAddress(vlc_gl_t *, const char *);
 
 /**
  * It creates an OpenGL vout display.
@@ -111,7 +112,7 @@ static int Open(vlc_object_t *object)
     sys->gl.lock = NULL;
     sys->gl.unlock = NULL;
     sys->gl.swap = Swap;
-    sys->gl.getProcAddress = NULL;
+    sys->gl.getProcAddress = GetProcAddress;
     sys->gl.sys = vd;
 
     video_format_t fmt = vd->fmt;
@@ -228,3 +229,8 @@ static void Swap(vlc_gl_t *gl)
     SwapBuffers(vd->sys->hGLDC);
 }
 
+static void *GetProcAddress(vlc_gl_t *gl, const char *name)
+{
+    return wglGetProcAddress(name);
+}
+