gst-gl: Remove duplicate declarations

This causes 'redefinition of typedef ...' errors on GCC 4.5.3

gst-libs/gst/gl/gbm/gstglwindow_gbm_egl.h

@@ -24,6 +24,7 @@
 #include <gbm.h>
 #include <gst/gl/gl.h>
 #include <gst/gl/egl/gstegl.h>
+#include <gst/gl/gbm/gstgldisplay_gbm.h>
 
 G_BEGIN_DECLS
 
@@ -37,8 +38,6 @@ G_BEGIN_DECLS
 typedef struct _GstGLWindowGBMEGL        GstGLWindowGBMEGL;
 typedef struct _GstGLWindowGBMEGLClass   GstGLWindowGBMEGLClass;
 
-typedef struct _GstGLDisplayGBM GstGLDisplayGBM;
-
 struct _GstGLWindowGBMEGL {
   /*< private >*/
   GstGLWindow parent;

gst-libs/gst/gl/gstgldebug.h

@@ -25,8 +25,6 @@
 
 G_BEGIN_DECLS
 
-typedef struct _GstGLAsyncDebug GstGLAsyncDebug;
-
 typedef gchar * (*GstGLAsyncDebugLogGetMessage) (gpointer user_data);
 
 /**

gst-libs/gst/gl/gstglfuncs.h

@@ -93,11 +93,11 @@ G_BEGIN_DECLS
   ret (GSTGLAPI *name) args;
 #define GST_GL_EXT_END()
 
-typedef struct _GstGLFuncs
+struct _GstGLFuncs
 {
 #include <gst/gl/glprototypes/all_functions.h>
   gpointer padding[GST_PADDING_LARGE*6];
-} GstGLFuncs;
+};
 
 #undef GST_GL_EXT_BEGIN
 #undef GST_GL_EXT_FUNCTION