xo-gc: refactor, focus on DX1Collector+MutationLogState

src/gc/MutationLogConfig.cpp

@@ -9,9 +9,11 @@ namespace xo {
     namespace mm {
 
         MutationLogConfig::MutationLogConfig(std::uint32_t ngen,
+                                             std::uint32_t survive,
                                              std::size_t mlog_z,
                                              bool debug_flag)
             : n_generation_{ngen},
+              n_survive_threshold_{survive},
               mutation_log_z_{mlog_z},
               debug_flag_{debug_flag}
         {}