Revert "third_party/protobuf: Update to HEAD (83d681ee2c)"

third_party/protobuf/cmake/libprotoc.cmake

Index: third_party/protobuf/cmake/libprotoc.cmake
diff --git a/third_party/protobuf/cmake/libprotoc.cmake b/third_party/protobuf/cmake/libprotoc.cmake
index 2d238449c22513baffc6d755c488cd90087a98ec..8df8986a113346114e82b1730f0d484366df26b0 100644
--- a/third_party/protobuf/cmake/libprotoc.cmake
+++ b/third_party/protobuf/cmake/libprotoc.cmake
@@ -72,7 +72,6 @@ set(libprotoc_files
   ${protobuf_source_dir}/src/google/protobuf/compiler/javanano/javanano_message_field.cc
   ${protobuf_source_dir}/src/google/protobuf/compiler/javanano/javanano_primitive_field.cc
   ${protobuf_source_dir}/src/google/protobuf/compiler/js/js_generator.cc
-  ${protobuf_source_dir}/src/google/protobuf/compiler/js/well_known_types_embed.cc
   ${protobuf_source_dir}/src/google/protobuf/compiler/objectivec/objectivec_enum.cc
   ${protobuf_source_dir}/src/google/protobuf/compiler/objectivec/objectivec_enum_field.cc
   ${protobuf_source_dir}/src/google/protobuf/compiler/objectivec/objectivec_extension.cc
@@ -85,7 +84,6 @@ set(libprotoc_files
   ${protobuf_source_dir}/src/google/protobuf/compiler/objectivec/objectivec_message_field.cc
   ${protobuf_source_dir}/src/google/protobuf/compiler/objectivec/objectivec_oneof.cc
   ${protobuf_source_dir}/src/google/protobuf/compiler/objectivec/objectivec_primitive_field.cc
-  ${protobuf_source_dir}/src/google/protobuf/compiler/php/php_generator.cc
   ${protobuf_source_dir}/src/google/protobuf/compiler/plugin.cc
   ${protobuf_source_dir}/src/google/protobuf/compiler/plugin.pb.cc
   ${protobuf_source_dir}/src/google/protobuf/compiler/python/python_generator.cc