added deprecated flag into ProtobufCFieldDescriptor->flags

[edmonds@fsi.io: resolve merge conflicts, add documentation]

protobuf-c/protobuf-c.h

@@ -250,7 +250,10 @@ struct _ProtobufCFieldDescriptor {
 typedef enum {
 	/* Set if the field is repeated and marked with the 'packed' option. */
 	PROTOBUF_C_FIELD_FLAG_PACKED		= (1 << 0),
-} ProtobufCFieldFlag;
+
+	/* Set if the field is marked with the 'deprecated' option. */
+	PROTOBUF_C_FIELD_FLAG_DEPRECATED	= (1 << 1),
+} ProtobufCFieldFlagType;
 
 /*
  * ProtobufCMessageDescriptor: description of a message.

protoc-c/c_field.cc

@@ -130,6 +130,9 @@ void FieldGenerator::GenerateDescriptorInitializerGeneric(io::Printer* printer,
    && descriptor_->options().packed())
     variables["flags"] += " | PROTOBUF_C_FIELD_FLAG_PACKED";
 
+  if (descriptor_->options().deprecated())
+    variables["flags"] += " | PROTOBUF_C_FIELD_FLAG_DEPRECATED";
+
   printer->Print(variables,
     "{\n"
     "  \"$proto_name$\",\n"