sha1_file: only expose empty object constants through git_hash_algo

There really isn't any case in which we want to expose the constants for
empty trees and blobs outside of using the hash algorithm abstraction.
Make these constants static and stop exposing the defines in cache.h.
Remove the constants which are no longer in use.

Signed-off-by: brian m. carlson <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: bk2204

cache.h

@@ -1013,22 +1013,6 @@ static inline void oidread(struct object_id *oid, const unsigned char *hash)
 	memcpy(oid->hash, hash, the_hash_algo->rawsz);
 }
 
-
-#define EMPTY_TREE_SHA1_HEX \
-	"4b825dc642cb6eb9a060e54bf8d69288fbee4904"
-#define EMPTY_TREE_SHA1_BIN_LITERAL \
-	 "\x4b\x82\x5d\xc6\x42\xcb\x6e\xb9\xa0\x60" \
-	 "\xe5\x4b\xf8\xd6\x92\x88\xfb\xee\x49\x04"
-extern const struct object_id empty_tree_oid;
-#define EMPTY_TREE_SHA1_BIN (empty_tree_oid.hash)
-
-#define EMPTY_BLOB_SHA1_HEX \
-	"e69de29bb2d1d6434b8b29ae775ad8c2e48c5391"
-#define EMPTY_BLOB_SHA1_BIN_LITERAL \
-	"\xe6\x9d\xe2\x9b\xb2\xd1\xd6\x43\x4b\x8b" \
-	"\x29\xae\x77\x5a\xd8\xc2\xe4\x8c\x53\x91"
-extern const struct object_id empty_blob_oid;
-
 static inline int is_empty_blob_sha1(const unsigned char *sha1)
 {
 	return !hashcmp(sha1, the_hash_algo->empty_blob->hash);

sha1_file.c

@@ -35,12 +35,21 @@
 /* The maximum size for an object header. */
 #define MAX_HEADER_LEN 32
 
+
+#define EMPTY_TREE_SHA1_BIN_LITERAL \
+	 "\x4b\x82\x5d\xc6\x42\xcb\x6e\xb9\xa0\x60" \
+	 "\xe5\x4b\xf8\xd6\x92\x88\xfb\xee\x49\x04"
+
+#define EMPTY_BLOB_SHA1_BIN_LITERAL \
+	"\xe6\x9d\xe2\x9b\xb2\xd1\xd6\x43\x4b\x8b" \
+	"\x29\xae\x77\x5a\xd8\xc2\xe4\x8c\x53\x91"
+
 const unsigned char null_sha1[GIT_MAX_RAWSZ];
 const struct object_id null_oid;
-const struct object_id empty_tree_oid = {
+static const struct object_id empty_tree_oid = {
 	EMPTY_TREE_SHA1_BIN_LITERAL
 };
-const struct object_id empty_blob_oid = {
+static const struct object_id empty_blob_oid = {
 	EMPTY_BLOB_SHA1_BIN_LITERAL
 };