Duplicate data between std.c.stdio and core.sys.posix.fcntl

[bioinfornatics]

i think they are some duplicate data between  std.c.stdio and 
core.sys.posix.fcntl

Both module define
        O_RDONLY O_WRONLY, O_RDWR, O_APPEND,O_CREAT, O_TRUNC, 
O_EXCL

maybe std.c.stdio should to use version poix winows and whatever 
to load these data