Use C++11 atomics

third_party/protobuf/src/Makefile.am

 ## Process this file with automake to produce Makefile.in
 
 if HAVE_ZLIB
 GZCHECKPROGRAMS = zcgzip zcgunzip
 GZHEADERS = google/protobuf/io/gzip_stream.h
 GZTESTS = google/protobuf/io/gzip_stream_unittest.sh
 else
 GZCHECKPROGRAMS =
 GZHEADERS =
 GZTESTS =
@@ skipping 74 matching lines @@
   google/protobuf/compiler/plugin.pb.h                          \
   google/protobuf/compiler/cpp/cpp_generator.h                  \
   google/protobuf/compiler/java/java_generator.h                \
   google/protobuf/compiler/python/python_generator.h
 
 lib_LTLIBRARIES = libprotobuf-lite.la libprotobuf.la libprotoc.la
 
 libprotobuf_lite_la_LIBADD = $(PTHREAD_LIBS)
 libprotobuf_lite_la_LDFLAGS = -version-info 8:0:0 -export-dynamic -no-undefined
 libprotobuf_lite_la_SOURCES =                                  \
-  google/protobuf/stubs/atomicops_internals_x86_gcc.cc         \
   google/protobuf/stubs/atomicops_internals_x86_msvc.cc        \
   google/protobuf/stubs/common.cc                              \
   google/protobuf/stubs/once.cc                                \
   google/protobuf/stubs/hash.h                                 \
   google/protobuf/stubs/map-util.h                             \
   google/protobuf/stubs/stl_util.h                             \
   google/protobuf/stubs/stringprintf.cc                        \
   google/protobuf/stubs/stringprintf.h                         \
   google/protobuf/extension_set.cc                             \
   google/protobuf/generated_message_util.cc                    \
@@ skipping 280 matching lines @@
 if HAVE_ZLIB
 zcgzip_LDADD = $(PTHREAD_LIBS) libprotobuf.la
 zcgzip_SOURCES = google/protobuf/testing/zcgzip.cc
 
 zcgunzip_LDADD = $(PTHREAD_LIBS) libprotobuf.la
 zcgunzip_SOURCES = google/protobuf/testing/zcgunzip.cc
 endif
 
 TESTS = protobuf-test protobuf-lazy-descriptor-test protobuf-lite-test \
         google/protobuf/compiler/zip_output_unittest.sh $(GZTESTS)