Add another warning to the libc++ Android.bp. am: 911760b18e am: 8d025e2a45 am: 8d14d97534

Original change: https://android-review.googlesource.com/c/platform/external/libcxx/+/1804478

Change-Id: I02520eeb0f9c63f2ea297d81c29b14361b33f4c7
diff --git a/Android.bp b/Android.bp
index e29a44c..3a38980 100644
--- a/Android.bp
+++ b/Android.bp
@@ -14,6 +14,10 @@
 // limitations under the License.
 //
 
+// NOTE: This project is out of date. See http://b/175635923 for details. Until
+// that is resolved it is not possible for us to update or expand access to
+// std::filesystem.
+
 package {
     default_applicable_licenses: ["external_libcxx_license"],
 }