Merge branch 'bc/hash-algo'

More abstraction of hash function from the codepath.

* bc/hash-algo:
  hash: update obsolete reference to SHA1_HEADER
  bulk-checkin: abstract SHA-1 usage
  csum-file: abstract uses of SHA-1
  csum-file: rename sha1file to hashfile
  read-cache: abstract away uses of SHA-1
  pack-write: switch various SHA-1 values to abstract forms
  pack-check: convert various uses of SHA-1 to abstract forms
  fast-import: switch various uses of SHA-1 to the_hash_algo
  sha1_file: switch uses of SHA-1 to the_hash_algo
  builtin/unpack-objects: switch uses of SHA-1 to the_hash_algo
  builtin/index-pack: improve hash function abstraction
  hash: create union for hash context allocation
  hash: move SHA-1 macros to hash.h

cache.h

@@ -16,31 +16,6 @@
 #include "sha1-array.h"
 #include "repository.h"
 
-#ifndef platform_SHA_CTX
-/*
- * platform's underlying implementation of SHA-1; could be OpenSSL,
- * blk_SHA, Apple CommonCrypto, etc...  Note that including
- * SHA1_HEADER may have already defined platform_SHA_CTX for our
- * own implementations like block-sha1 and ppc-sha1, so we list
- * the default for OpenSSL compatible SHA-1 implementations here.
- */
-#define platform_SHA_CTX	SHA_CTX
-#define platform_SHA1_Init	SHA1_Init
-#define platform_SHA1_Update	SHA1_Update
-#define platform_SHA1_Final    	SHA1_Final
-#endif
-
-#define git_SHA_CTX		platform_SHA_CTX
-#define git_SHA1_Init		platform_SHA1_Init
-#define git_SHA1_Update		platform_SHA1_Update
-#define git_SHA1_Final		platform_SHA1_Final
-
-#ifdef SHA1_MAX_BLOCK_SIZE
-#include "compat/sha1-chunked.h"
-#undef git_SHA1_Update
-#define git_SHA1_Update		git_SHA1_Update_Chunked
-#endif
-
 #include <zlib.h>
 typedef struct git_zstream {
 	z_stream z;