packfile: drop sha1_pack_name()

The sha1_pack_name() function has a few ugly bits:

  - it writes into a static strbuf (and not even a ring buffer of them),
    which can lead to subtle invalidation problems

  - it uses the term "sha1", but it's really using the_hash_algo, which
    could be sha256

There's only one caller of it left. And in fact that caller is better
off using the underlying odb_pack_name() function itself, since it's
just copying the result into its own strbuf anyway.

Converting that caller lets us get rid of this now-obselete function.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Taylor Blau <me@ttaylorr.com>

packfile.h

@@ -31,13 +31,6 @@ struct pack_entry {
  */
 char *odb_pack_name(struct strbuf *buf, const unsigned char *sha1, const char *ext);
 
-/*
- * Return the name of the (local) packfile with the specified sha1 in
- * its name.  The return value is a pointer to memory that is
- * overwritten each time this function is called.
- */
-char *sha1_pack_name(const unsigned char *sha1);
-
 /*
  * Return the name of the (local) pack index file with the specified
  * sha1 in its name.  The return value is a pointer to memory that is