[RenderEngine] Make use of EGL_KHR_surfaceless_context.

Per
https://www.khronos.org/registry/EGL/extensions/KHR/EGL_KHR_surfaceless_context.txt,
when EGL_KHR_surfaceless_context is present, we can make the context current
without specifying draw and read surface, thus we no longer need to create a
1x1 buffer surface.

BUG: 35315015
Test: Build, flash, boot.
Change-Id: Ia5f19cf0f9561bb660708b5a2ae0187593422210
diff --git a/libs/renderengine/gl/GLES20RenderEngine.h b/libs/renderengine/gl/GLES20RenderEngine.h
index 6c50938..77dba62 100644
--- a/libs/renderengine/gl/GLES20RenderEngine.h
+++ b/libs/renderengine/gl/GLES20RenderEngine.h
@@ -112,6 +112,10 @@
     };
 
     static GlesVersion parseGlesVersion(const char* str);
+    static EGLContext createEglContext(EGLDisplay display, EGLConfig config,
+                                       EGLContext shareContext, bool useContextPriority);
+    static EGLSurface createDummyEglPbufferSurface(EGLDisplay display, EGLConfig config,
+                                                   int hwcFormat);
 
     // A data space is considered HDR data space if it has BT2020 color space
     // with PQ or HLG transfer function.