builtin/{grep,log}.: don't define "USE_THE_INDEX_COMPATIBILITY_MACROS"

Adding "USE_THE_INDEX_COMPATIBILITY_MACROS" to these two appears to
have been unnecessary from the start, as going back and compiling
f8adbec9fe (cache.h: flip NO_THE_INDEX_COMPATIBILITY_MACROS switch,
2019-01-24) without that addition works.

Let's not have these ask for the compatibility macros from cache.h
that they don't need.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/grep.c

@@ -3,7 +3,6 @@
  *
  * Copyright (c) 2006 Junio C Hamano
  */
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
 #include "cache.h"
 #include "repository.h"
 #include "config.h"

builtin/log.c

@@ -4,7 +4,6 @@
  * (C) Copyright 2006 Linus Torvalds
  *		 2006 Junio Hamano
  */
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
 #include "cache.h"
 #include "config.h"
 #include "refs.h"