Remove obsolete GLES2 backend code

This code currently isn't compiled (and cannot compile).

We plan to re-add OpenGL ES-based renderer(s) in Godot 4.0 alongside Vulkan
(probably ES 3.0, possibly also a low-end ES 2.0), but the code will be quite
different so it's not relevant to keep this old Godot 3.2 code.

The `drivers/gles2` code from the `3.2` branch can be used as a reference for
a potential new implementation.

platform/android/display_server_android.cpp

@@ -36,9 +36,6 @@
 #include "java_godot_wrapper.h"
 #include "os_android.h"
 
-#if defined(OPENGL_ENABLED)
-#include "drivers/gles2/rasterizer_gles2.h"
-#endif
 #if defined(VULKAN_ENABLED)
 #include "drivers/vulkan/rendering_device_vulkan.h"
 #include "platform/android/vulkan/vulkan_context_android.h"

platform/iphone/os_iphone.mm

@@ -46,10 +46,6 @@
 #import <UIKit/UIKit.h>
 #import <dlfcn.h>
 
-#if defined(OPENGL_ENABLED)
-#include "drivers/gles2/rasterizer_gles2.h"
-#endif
-
 #if defined(VULKAN_ENABLED)
 #include "servers/rendering/rasterizer_rd/rasterizer_rd.h"
 #import <QuartzCore/CAMetalLayer.h>

platform/iphone/platform_config.h

@@ -30,8 +30,6 @@
 
 #include <alloca.h>
 
-#define GLES2_INCLUDE_H <ES2/gl.h>
-
 #define PLATFORM_REFCOUNT
 
 #define PTHREAD_RENAME_SELF

platform/linuxbsd/display_server_x11.cpp

@@ -39,10 +39,6 @@
 #include "main/main.h"
 #include "scene/resources/texture.h"
 
-#if defined(OPENGL_ENABLED)
-#include "drivers/gles2/rasterizer_gles2.h"
-#endif
-
 #if defined(VULKAN_ENABLED)
 #include "servers/rendering/rasterizer_rd/rasterizer_rd.h"
 #endif

platform/linuxbsd/platform_config.h

@@ -35,5 +35,3 @@
 #include <stdlib.h>
 #define PTHREAD_BSD_SET_NAME
 #endif
-
-#define GLES2_INCLUDE_H "thirdparty/glad/glad/glad.h"

platform/osx/display_server_osx.mm

@@ -45,7 +45,6 @@
 #include <IOKit/hid/IOHIDLib.h>
 
 #if defined(OPENGL_ENABLED)
-#include "drivers/gles2/rasterizer_gles2.h"
 //TODO - reimplement OpenGLES
 
 #import <AppKit/NSOpenGLView.h>

platform/osx/platform_config.h

@@ -30,5 +30,4 @@
 
 #include <alloca.h>
 
-#define GLES2_INCLUDE_H "thirdparty/glad/glad/glad.h"
 #define PTHREAD_RENAME_SELF

platform/uwp/os_uwp.cpp

@@ -35,7 +35,6 @@
 
 #include "core/io/marshalls.h"
 #include "core/project_settings.h"
-#include "drivers/gles2/rasterizer_gles2.h"
 #include "drivers/unix/ip_unix.h"
 #include "drivers/windows/dir_access_windows.h"
 #include "drivers/windows/file_access_windows.h"

platform/windows/platform_config.h

@@ -29,5 +29,3 @@
 /*************************************************************************/
 
 #include <malloc.h>
-
-#define GLES2_INCLUDE_H "thirdparty/glad/glad/glad.h"