Bug 944003 - Build toolkit/components/protobuf in unified mode; r=glandium

toolkit/components/protobuf/moz.build

@@ -30,7 +30,7 @@ EXPORTS.protobuf.google.protobuf.io += [
     'google/protobuf/package_info.h',
 ]
 
-SOURCES += [
+UNIFIED_SOURCES += [
     'google/protobuf/extension_set.cc',
     'google/protobuf/generated_message_util.cc',
     'google/protobuf/io/coded_stream.cc',