Oops. I forgot to 'fclose()' the file after saving the xml

Oops. I forgot to 'fclose()' the file after saving the xml

It never actually triggered anything for me, but any buffered data might
be lost, especially if you force-exit the application after saving a
dive log.

This probably explains a corrupted (truncated) dive file report from
Nathan Samson.

Reported-by: Nathan Samson <https://github.com/nathansamson>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>