https://issues.dlang.org/show_bug.cgi?id=19431

          Issue ID: 19431
           Summary: Add _r variants of various stdc time functions.
           Product: D
           Version: D2
          Hardware: All
                OS: Other
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: druntime
          Assignee: nobody@puremagic.com
          Reporter: stanislav.blinov@gmail.com

These are missing from core.stdc.time:

char *asctime_r(const struct tm *tm, char *buf);
char *ctime_r(const time_t *timep, char *buf);
struct tm *gmtime_r(const time_t *timep, struct tm *result);
struct tm *localtime_r(const time_t *timep, struct tm *result);

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