Enable IMG_context_priority depending on availability

The config value from the config store can still be used to
override it.

Test: Enable gpu completion tracing, observe how SF preempts other
GPU drawing
Bug: 64674361

Change-Id: Id2f6f11019c2e6cae078fb9e64e3d9d72e42533c
diff --git a/services/surfaceflinger/RenderEngine/GLExtensions.h b/services/surfaceflinger/RenderEngine/GLExtensions.h
index 81078e0..0d8c10b 100644
--- a/services/surfaceflinger/RenderEngine/GLExtensions.h
+++ b/services/surfaceflinger/RenderEngine/GLExtensions.h
@@ -41,6 +41,7 @@
     bool mHasWaitSync = false;
     bool mHasImageCrop = false;
     bool mHasProtectedContent = false;
+    bool mHasContextPriority = false;
 
     String8 mVendor;
     String8 mRenderer;
@@ -67,6 +68,7 @@
     bool hasWaitSync() const { return mHasWaitSync; }
     bool hasImageCrop() const { return mHasImageCrop; }
     bool hasProtectedContent() const { return mHasProtectedContent; }
+    bool hasContextPriority() const { return mHasContextPriority; }
 
     void initWithGLStrings(GLubyte const* vendor, GLubyte const* renderer, GLubyte const* version,
                            GLubyte const* extensions);