make: unifdef for PARALLEL (undefined, this relates to the old pmake)

*** 53,65 ****
  #include <mksh/i18n.h>          /* get_char_semantics_value() */
  #include <mksh/macro.h>         /* getvar(), expand_value() */
  #include <mksh/misc.h>          /* getmem() */
  #include <poll.h>
  
- #ifdef PARALLEL
- #       include <rx/api.h>
- #endif
  
  #include <signal.h>
  
  #       include <stropts.h>
  
--- 53,62 ----
*** 71,83 ****
  #include <unistd.h>             /* close() */
  
  /*
   * Defined macros
   */
- #ifndef PARALLEL
  #       define LOCALHOST "localhost"
- #endif
  
  #define MAXRULES 100
  
  #if defined(DISTRIBUTED) || defined(MAKETOOL) /* tolik */
  #define SEND_MTOOL_MSG(cmds) \
--- 68,78 ----
*** 545,559 ****
                          delete_query_chain(line->body.line.query);
                  }
                  line->body.line.query = out_of_date_list;
          }
  
- #ifdef PARALLEL
-         if (doing_subtree) {
-                 parallel = false;
-         }
- #endif
  
  /*
   * If the target is a :: type, do not try to find the rule for the target,
   * all actions will be taken by separate branches.
   * Else, we try to find an implicit rule using various methods,
--- 540,549 ----