This allows rewinding a directory by specifying the cookie 0, after already scrolling a directory. This allows zig and clang functionality to work which expect this. This also fixes the case where a directory was allowed to be seeked. This is prohibited by the current version of wasi-testsuite. Signed-off-by: Adrian Cole <adrian@tetrate.io> Co-authored-by: Takeshi Yoneda <takeshi@tetrate.io>