hex: drop sha1_to_hex_r()

There are no callers left; everybody uses oid_to_hex_r() or
hash_to_hex_algop_r(). This used to actually be the underlying
implementation for oid_to_hex_r(), but that's no longer the case since
47edb64997 (hex: introduce functions to print arbitrary hashes,
2018-11-14).

Let's get rid of it to de-clutter and to make sure nobody uses it.
Likewise we can drop the coccinelle rules that mention it, since the
compiler will make it quite clear that the code does not work.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

cache.h

@@ -1462,7 +1462,6 @@ int hex_to_bytes(unsigned char *binary, const char *hex, size_t len);
  *   printf("%s -> %s", sha1_to_hex(one), sha1_to_hex(two));
  */
 char *hash_to_hex_algop_r(char *buffer, const unsigned char *hash, const struct git_hash_algo *);
-char *sha1_to_hex_r(char *out, const unsigned char *sha1);
 char *oid_to_hex_r(char *out, const struct object_id *oid);
 char *hash_to_hex_algop(const unsigned char *hash, const struct git_hash_algo *);	/* static buffer result! */
 char *sha1_to_hex(const unsigned char *sha1);						/* same static buffer */

contrib/coccinelle/object_id.cocci

@@ -25,23 +25,6 @@ struct object_id *OIDPTR;
 + oid_to_hex(OIDPTR)
   ...>}
 
-@@
-expression E;
-struct object_id OID;
-@@
-- sha1_to_hex_r(E, OID.hash)
-+ oid_to_hex_r(E, &OID)
-
-@@
-identifier f != oid_to_hex_r;
-expression E;
-struct object_id *OIDPTR;
-@@
-   f(...) {<...
-- sha1_to_hex_r(E, OIDPTR->hash)
-+ oid_to_hex_r(E, OIDPTR)
-  ...>}
-
 @@
 struct object_id OID;
 @@

hex.c

@@ -90,11 +90,6 @@ char *hash_to_hex_algop_r(char *buffer, const unsigned char *hash,
 	return buffer;
 }
 
-char *sha1_to_hex_r(char *buffer, const unsigned char *sha1)
-{
-	return hash_to_hex_algop_r(buffer, sha1, &hash_algos[GIT_HASH_SHA1]);
-}
-
 char *oid_to_hex_r(char *buffer, const struct object_id *oid)
 {
 	return hash_to_hex_algop_r(buffer, oid->hash, the_hash_algo);