Update //third_party/protobuf to version 3.

third_party/protobuf/cmake/libprotobuf-lite.cmake

+set(libprotobuf_lite_files
+  ${protobuf_source_dir}/src/google/protobuf/arena.cc
+  ${protobuf_source_dir}/src/google/protobuf/arenastring.cc
+  ${protobuf_source_dir}/src/google/protobuf/extension_set.cc
+  ${protobuf_source_dir}/src/google/protobuf/generated_message_util.cc
+  ${protobuf_source_dir}/src/google/protobuf/io/coded_stream.cc
+  ${protobuf_source_dir}/src/google/protobuf/io/zero_copy_stream.cc
+  ${protobuf_source_dir}/src/google/protobuf/io/zero_copy_stream_impl_lite.cc
+  ${protobuf_source_dir}/src/google/protobuf/message_lite.cc
+  ${protobuf_source_dir}/src/google/protobuf/repeated_field.cc
+  ${protobuf_source_dir}/src/google/protobuf/stubs/atomicops_internals_x86_gcc.cc
+  ${protobuf_source_dir}/src/google/protobuf/stubs/atomicops_internals_x86_msvc.cc
+  ${protobuf_source_dir}/src/google/protobuf/stubs/bytestream.cc
+  ${protobuf_source_dir}/src/google/protobuf/stubs/common.cc
+  ${protobuf_source_dir}/src/google/protobuf/stubs/int128.cc
+  ${protobuf_source_dir}/src/google/protobuf/stubs/once.cc
+  ${protobuf_source_dir}/src/google/protobuf/stubs/status.cc
+  ${protobuf_source_dir}/src/google/protobuf/stubs/statusor.cc
+  ${protobuf_source_dir}/src/google/protobuf/stubs/stringpiece.cc
+  ${protobuf_source_dir}/src/google/protobuf/stubs/stringprintf.cc
+  ${protobuf_source_dir}/src/google/protobuf/stubs/structurally_valid.cc
+  ${protobuf_source_dir}/src/google/protobuf/stubs/strutil.cc
+  ${protobuf_source_dir}/src/google/protobuf/stubs/time.cc
+  ${protobuf_source_dir}/src/google/protobuf/wire_format_lite.cc
+)
+
+add_library(libprotobuf-lite ${protobuf_SHARED_OR_STATIC}
+  ${libprotobuf_lite_files})
+target_link_libraries(libprotobuf-lite ${CMAKE_THREAD_LIBS_INIT})
+target_include_directories(libprotobuf-lite PUBLIC ${protobuf_source_dir}/src)
+if(MSVC AND protobuf_BUILD_SHARED_LIBS)
+  target_compile_definitions(libprotobuf-lite
+    PUBLIC  PROTOBUF_USE_DLLS
+    PRIVATE LIBPROTOBUF_EXPORTS)
+endif()
+set_target_properties(libprotobuf-lite PROPERTIES
+    OUTPUT_NAME ${LIB_PREFIX}protobuf-lite
+    DEBUG_POSTFIX "${protobuf_DEBUG_POSTFIX}")