[godot] Fix compilation errors with 3.5.3, fix const correctness.

spine-godot/spine_godot/SpineAtlasResource.cpp

@@ -232,6 +232,7 @@ Error SpineAtlasResource::save_to_file(const String &path) {
 	return OK;
 }
 
+#if VERSION_MAJOR > 3
 Error SpineAtlasResource::copy_from(const Ref<Resource> &p_resource) {
 	auto error = Resource::copy_from(p_resource);
 	if (error != OK) return error;
@@ -251,6 +252,7 @@ Error SpineAtlasResource::copy_from(const Ref<Resource> &p_resource) {
 
 	return OK;
 }
+#endif
 
 #if VERSION_MAJOR > 3
 RES SpineAtlasResourceFormatLoader::load(const String &path, const String &original_path, Error *error, bool use_sub_threads, float *progress, CacheMode cache_mode) {

spine-godot/spine_godot/SpineAtlasResource.h

@@ -45,8 +45,8 @@ class SpineAtlasResource : public Resource {
 protected:
 	static void _bind_methods();
 
-	spine::Atlas *atlas;
-	GodotSpineTextureLoader *texture_loader;
+	mutable spine::Atlas *atlas;
+	mutable GodotSpineTextureLoader *texture_loader;
 
 	String source_path;
 	String atlas_data;
@@ -69,7 +69,9 @@ public:
 
 	Error save_to_file(const String &path);// .spatlas
 
+#if VERSION_MAJOR > 3
 	virtual Error copy_from(const Ref<Resource> &p_resource);
+#endif
 
 	String get_source_path();
 
@@ -77,7 +79,7 @@ public:
 
 	Array get_normal_maps();
 
-	const void clear_native_data() {
+	void clear_native_data() const {
 		this->atlas = nullptr;
 		this->texture_loader = nullptr;
 	}

spine-godot/spine_godot/SpineSkeletonFileResource.cpp

@@ -28,11 +28,13 @@
  *****************************************************************************/
 
 #include "SpineSkeletonFileResource.h"
+#if VERSION_MAJOR > 3
 #include "core/error/error_list.h"
 #include "core/error/error_macros.h"
-#if VERSION_MAJOR > 3
 #include "core/io/file_access.h"
 #else
+#include "core/error_list.h"
+#include "core/error_macros.h"
 #include "core/os/file_access.h"
 #endif
 #include <spine/Json.h>
@@ -160,6 +162,7 @@ Error SpineSkeletonFileResource::save_to_file(const String &path) {
 	return OK;
 }
 
+#if VERSION_MAJOR > 3
 Error SpineSkeletonFileResource::copy_from(const Ref<Resource> &p_resource) {
 	auto error = Resource::copy_from(p_resource);
 	if (error != OK) return error;
@@ -169,6 +172,7 @@ Error SpineSkeletonFileResource::copy_from(const Ref<Resource> &p_resource) {
 	emit_signal(SNAME("skeleton_file_changed"));
 	return OK;
 }
+#endif
 
 #if VERSION_MAJOR > 3
 RES SpineSkeletonFileResourceFormatLoader::load(const String &path, const String &original_path, Error *error, bool use_sub_threads, float *progress, CacheMode cache_mode) {

spine-godot/spine_godot/SpineSkeletonFileResource.h

@@ -53,7 +53,9 @@ public:
 
 	Error save_to_file(const String &path);
 
+#if VERSION_MAJOR > 3
 	virtual Error copy_from(const Ref<Resource> &p_resource);
+#endif
 };
 
 class SpineSkeletonFileResourceFormatLoader : public ResourceFormatLoader {