Remove llndk_headers module

Use a cc_library_headers module with llndk.llndk_headers: true instead
of an llndk_headers module.

Bug: 170784825
Test: m checkbuild
Test: compare out/soong/build.ninja
Change-Id: I6717ab613adde20652f6e861ca7179e202e63a83
diff --git a/opengl/Android.bp b/opengl/Android.bp
index 748f795..16ce15b 100644
--- a/opengl/Android.bp
+++ b/opengl/Android.bp
@@ -68,11 +68,9 @@
     name: "gl_headers",
     vendor_available: true,
     export_include_dirs: ["include"],
-}
-
-llndk_headers {
-    name: "gl_llndk_headers",
-    export_include_dirs: ["include"],
+    llndk: {
+        llndk_headers: true,
+    },
 }
 
 subdirs = [