Update third_party/protobuf to protobuf-v3.0.0-beta-3

third_party/protobuf/examples/README.txt

 This directory contains example code that uses Protocol Buffers to manage an
 address book.  Two programs are provided, each with three different
 implementations, one written in each of C++, Java, and Python.  The add_person
 example adds a new person to an address book, prompting the user to input
 the person's information.  The list_people example lists people already in the
 address book.  The examples use the exact same format in all three languages,
 so you can, for example, use add_person_java to create an address book and then
 use list_people_python to read it.
 
 You must install the protobuf package before you can build these.
@@ skipping 17 matching lines @@
 "-lpthread" from the linker commands (perhaps replacing it with something else).
 We didn't do this automatically because we wanted to keep the example simple.
 
 ## Go ##
 
 The Go example requires a plugin to the protocol buffer compiler, so it is not
 build with all the other examples.  See:
   https://github.com/golang/protobuf
 for more information about Go protocol buffer support.
 
-First, install the the Protocol Buffers compiler (protoc).
+First, install the Protocol Buffers compiler (protoc).
 Then, install the Go Protocol Buffers plugin
 ($GOPATH/bin must be in your $PATH for protoc to find it):
   go get github.com/golang/protobuf/protoc-gen-go
 
 Build the Go samples in this directory with "make go".  This creates the
 following executable files in the current directory:
   add_person_go      list_people_go
 To run the example:
   ./add_person_go addressbook.data
 to add a person to the protocol buffer encoded file addressbook.data.  The file
 is created if it does not exist.  To view the data, run:
   ./list_people_go addressbook.data
 
 Observe that the C++, Python, and Java examples in this directory run in a
 similar way and can view/modify files created by the Go example and vice
 versa.