Squashed 'libs/protobuf/' content from commit fcd3b9a85

git-subtree-dir: libs/protobuf
git-subtree-split: fcd3b9a85ef36e46643dc30176cea1a7ad62e02b

php/tests/proto_previous/test_previously_unreserved_message.proto

@@ -0,0 +1,5 @@
+syntax = "proto3";
+
+package previous;
+
+message readonly {}