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.cpp b/services/surfaceflinger/RenderEngine/GLExtensions.cpp
index e6e4df1..dc09a37 100644
--- a/services/surfaceflinger/RenderEngine/GLExtensions.cpp
+++ b/services/surfaceflinger/RenderEngine/GLExtensions.cpp
@@ -106,6 +106,9 @@
     if (hasEGLExtension("EGL_EXT_protected_content")) {
         mHasProtectedContent = true;
     }
+    if (hasEGLExtension("EGL_IMG_context_priority")) {
+        mHasContextPriority = true;
+    }
 }
 
 char const* GLExtensions::getEGLVersion() const {