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>

save-xml.c

@@ -193,4 +193,5 @@ void save_dives(const char *filename)
 	for (i = 0; i < dive_table.nr; i++)
 		save_dive(f, get_dive(i));
 	fprintf(f, "</dives>\n");
+	fclose(f);
 }