Fix S_ISDOOR/S_IFDOOR spelling mistake.

This fix has been sent upstream.

--- tree-1.7.0/tree.c.orig 2016-03-03 06:04:25.447097615 -0800

+++ tree-1.7.0/tree.c 2016-03-03 06:04:49.600428587 -0800

@@ -1258,7 +1258,7 @@

else if (m == S_IFIFO) return '|';

else if (m == S_IFLNK) return '@'; /* Here, but never actually used though. */

#ifdef S_IFDOOR

- else if (m == S_ISDOOR) return '>';

+ else if (m == S_IFDOOR) return '>';

#endif

else if ((m == S_IFREG) && (mode & (S_IXUSR | S_IXGRP | S_IXOTH))) return '*';

return 0;