unchanged:
--- protobuf-cleaned/src/google/protobuf/generated_message_util.cc	2015-12-30 13:21:46.000000000 -0800
+++ protobuf-patched/src/google/protobuf/generated_message_util.cc	2016-03-31 13:25:32.180017848 -0700
@@ -60,6 +60,12 @@
   OnShutdown(&DeleteEmptyString);
 }
 
+const ::std::string& GetEmptyString() {
+  ::google::protobuf::GoogleOnceInit(&empty_string_once_init_, &InitEmptyString);
+  return GetEmptyStringAlreadyInited();
+}
+
+
 int StringSpaceUsedExcludingSelf(const string& str) {
   const void* start = &str;
   const void* end = &str + 1;
only in patch2:
unchanged:
--- protobuf-cleaned/src/google/protobuf/generated_message_util.h	2015-12-30 13:21:46.000000000 -0800
+++ protobuf-patched/src/google/protobuf/generated_message_util.h	2016-03-31 13:25:40.252007316 -0700
@@ -84,10 +84,8 @@
   assert(empty_string_ != NULL);
   return *empty_string_;
 }
-LIBPROTOBUF_EXPORT inline const ::std::string& GetEmptyString() {
-  ::google::protobuf::GoogleOnceInit(&empty_string_once_init_, &InitEmptyString);
-  return GetEmptyStringAlreadyInited();
-}
+
+LIBPROTOBUF_EXPORT const ::std::string& GetEmptyString();
 
 LIBPROTOBUF_EXPORT int StringSpaceUsedExcludingSelf(const string& str);