blame: remove unneeded dependency on blob.h

With commit 21666f1 ("convert object type handling from a string to a
number", 2007-02-26), there was no longer a need for blame.c to include
blob.h but it was not removed.

Signed-off-by: Jeff Smith <whydoubt@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/blame.c

@@ -8,7 +8,6 @@
 #include "cache.h"
 #include "refs.h"
 #include "builtin.h"
-#include "blob.h"
 #include "commit.h"
 #include "tag.h"
 #include "tree-walk.h"