Remove unused types

They're not doing anything, so might as well get rid of them.
diff --git a/src/google/protobuf/extension_set.cc b/src/google/protobuf/extension_set.cc
index 6629ec0..ff2fc35 100644
--- a/src/google/protobuf/extension_set.cc
+++ b/src/google/protobuf/extension_set.cc
@@ -280,7 +280,7 @@
 
 namespace {
 
-enum Cardinality {
+enum {
   REPEATED,
   OPTIONAL
 };
diff --git a/src/google/protobuf/stubs/common.cc b/src/google/protobuf/stubs/common.cc
index 7c17d97..f1a688d 100644
--- a/src/google/protobuf/stubs/common.cc
+++ b/src/google/protobuf/stubs/common.cc
@@ -342,7 +342,6 @@
 
 namespace internal {
 
-typedef void OnShutdownFunc();
 struct ShutdownData {
   ~ShutdownData() {
     std::reverse(functions.begin(), functions.end());