Delete RenderEngine unused code

* V0 skia implementation beat the prior change deleting unused code, so
delete bindExternalTextureBuffer there.
* Remove useNativeFenceSync, now that there's no more usages
* Remove impl::RenderEngine, since there's no need for a private
impl-superclass spanning every RenderEngine implementation
* Clean up mock/RenderEngine

Bug: 168553972
Test: builds
Change-Id: I6f760510656b90b30d86b04fc70c19067a4491cd
diff --git a/libs/renderengine/gl/GLESRenderEngine.h b/libs/renderengine/gl/GLESRenderEngine.h
index c72b7f9..1779994 100644
--- a/libs/renderengine/gl/GLESRenderEngine.h
+++ b/libs/renderengine/gl/GLESRenderEngine.h
@@ -48,7 +48,7 @@
 class GLImage;
 class BlurFilter;
 
-class GLESRenderEngine : public impl::RenderEngine {
+class GLESRenderEngine : public RenderEngine {
 public:
     static std::unique_ptr<GLESRenderEngine> create(const RenderEngineCreationArgs& args);
 
@@ -231,6 +231,10 @@
     // supports sRGB, DisplayP3 color spaces.
     const bool mUseColorManagement = false;
 
+    // Whether only shaders performing tone mapping from HDR to SDR will be generated on
+    // primeCache().
+    const bool mPrecacheToneMapperShaderOnly = false;
+
     // Cache of GL images that we'll store per GraphicBuffer ID
     std::unordered_map<uint64_t, std::unique_ptr<Image>> mImageCache GUARDED_BY(mRenderingMutex);
     std::unordered_map<uint32_t, std::optional<uint64_t>> mTextureView;