Fix preprocessor error with deprecated macros intended to be used as an attribute value

(cherry-picked from commit c9d5832845)

src/serialization/preprocessor.cpp

@@ -1238,6 +1238,7 @@ bool preprocessor_data::get_chunk()
 								deprecation_detail += '\n';
 							}
 							deprecation_detail = read_rest_of_line();
+							skip_eol();
 						}
 					}