rem: long int v = _POSIX2_VERSION;
add: long int v = DEFAULT_POSIX2_VERSION;
context: posix2_version (void){  long int v = _POSIX2_VERSION;  char const *s = getenv ("_POSIX2_VERSION");  if (s && *s)    {      char *e;      long int i = strtol (s, &e, 10);      if (! *e)	v = i;    }  return v < INT_MIN ? INT_MIN : v < INT_MAX ? v : INT_MAX;}