make: unifdef for other OSes (undefined)

*** 440,454 ****
  
  #include <unistd.h>     /* sysconf(_SC_NPROCESSORS_ONLN) */
  #include <sys/ipc.h>            /* ftok() */
  #include <sys/shm.h>            /* shmget(), shmat(), shmdt(), shmctl() */
  #include <semaphore.h>          /* sem_init(), sem_trywait(), sem_post(), sem_destroy() */
- #if defined(linux)
- #define LOADAVG_1MIN    0
- #else
  #include <sys/loadavg.h>        /* getloadavg() */
- #endif /* linux */
  
  /*
   *      adjust_pmake_max_jobs (int pmake_max_jobs)
   *
   *      Parameters:
--- 440,450 ----
*** 2172,2186 ****
                                          DO_CHECK(fprintf(scrfp, NOCATGETS("/usr/bin/printf '%%s\\n' %s\n"), mbst));
                                  }
                                  if (!do_not_exec_rule ||
                                      !working_on_targets ||
                                      always_exec) {
- #if defined(linux)
-                                         if (0 != strcmp(shell->string_mb, (char*)NOCATGETS("/bin/sh"))) {
-                                                 DO_CHECK(fprintf(scrfp, NOCATGETS("%s -c %s\n"), shell->string_mb, cmd));
-                                         } else
- #endif
                                          DO_CHECK(fprintf(scrfp, NOCATGETS("%s -ce %s\n"), shell->string_mb, cmd));
                                          DO_CHECK(fputs(NOCATGETS("__DMAKECMDEXITSTAT=$?\nif [ ${__DMAKECMDEXITSTAT} -ne 0 ]; then\n"), scrfp));
                                          if (ignore) {
                                                  DO_CHECK(fprintf(scrfp, NOCATGETS("\techo %s ${__DMAKECMDEXITSTAT} %s\n"),
                                                          catgets(catd, 1, 343, "\"*** Error code"),
--- 2168,2177 ----