[software coproarchaeology] dentry.h: kill a mysterious comment

there's a strange comment in front of d_lookup() declaration:

/* appendix may either be NULL or be used for transname suffixes */

Looks like nobody had been curious enough to track its history;
it predates git, it predates bitkeeper and if you look through
the pre-BK trees, you finally arrive at this in 2.1.44-for-davem:
  /* appendix may either be NULL or be used for transname suffixes */
 -extern struct dentry * d_lookup(struct inode * dir, struct qstr * name,
 -                               struct qstr * appendix);
 +extern struct dentry * d_lookup(struct dentry * dir, struct qstr * name);
In other words, it refers to the third argument d_lookup() used to have
back then.  It had been introduced in 2.1.43-pre, on June 12 1997,
along with d_lookup(), only to be removed by July 4 1997, presumably
when the Cthulhu-awful thing it used to be used for (look for
CONFIG_TRANS_NAMES in 2.1.43-pre, and keep a heavy-duty barfbag
ready) had been, er, noticed and recognized for what it had been.

Despite the appendectomy, the comment remained.  Some things really
need to be put out of their misery...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Author: Al Viro

include/linux/dcache.h

@@ -270,7 +270,6 @@ extern void d_move(struct dentry *, struct dentry *);
 extern void d_exchange(struct dentry *, struct dentry *);
 extern struct dentry *d_ancestor(struct dentry *, struct dentry *);
 
-/* appendix may either be NULL or be used for transname suffixes */
 extern struct dentry *d_lookup(const struct dentry *, const struct qstr *);
 extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *);