cygport: Request to prevent loss and leak of time information

[Thomas Wolff]

Hi,
in addition to the recent request to set anonymous/generic user 
information in the tar archives,
I'd like to suggest also to apply a careful policy about timestamps:

  * Preserve timestamp information for original files: download upstream
    archive with server timestamp (wget -N / curl -R), keep its
    timestamp and that of patch and cygport files when copying to the
    staging directory for the src archive (cp -p), keep their timestamps
    when creating the archive (default).
  * Hide timestamp information for local build files: clear clock value
    when creating binary and debug archives (tar --mtime=00:00).

Kind regards,
Thomas