Update the NOTICE file from BoringSSL.

Test: n/a (metadata-only change)
diff --git a/UPDATING b/UPDATING
index 343ca18..f95b9d5 100755
--- a/UPDATING
+++ b/UPDATING
@@ -16,6 +16,7 @@
 rm -Rf linux-aarch64/ linux-arm/ linux-x86/ linux-x86_64/ mac-x86/ mac-x86_64/ win-x86_64/ win-x86/
 python src/util/generate_build_files.py android
 python src/util/generate_build_files.py eureka
+cp src/LICENSE NOTICE
 
 git add .
 git commit -m "external/boringssl: Sync to ${new_revision}.