[PATCH] t: use configured TAR instead of tar

["Đoàn Trần Công Danh" <congdanhqx@gmail.com>]

Despite that tar is available everywhere, it's not required by POSIX.
And, we're allow users to specify which tar they want to use in Makefile
knobs, and we prefer GNU tar in autotools script.

In our testsuite, 7 out of 9 tar-required-tests use "$TAR", the other
two use "tar".

Let's change the remaining two tests to "$TAR".

Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com>
---

 I found this when trying to remove tar from a chroot that used to test Git,
 such chroot has bsdtar, so I tried to set "TAR = bsdtar" in config.mak

 t/t3513-revert-submodule.sh | 4 ++--
 t/t6041-bisect-submodule.sh | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/t/t3513-revert-submodule.sh b/t/t3513-revert-submodule.sh
index 74cd96e582..8bfe3ed246 100755
--- a/t/t3513-revert-submodule.sh
+++ b/t/t3513-revert-submodule.sh
@@ -14,7 +14,7 @@ test_description='revert can handle submodules'
 git_revert () {
 	git status -su >expect &&
 	ls -1pR * >>expect &&
-	tar cf "$TRASH_DIRECTORY/tmp.tar" * &&
+	"$TAR" cf "$TRASH_DIRECTORY/tmp.tar" * &&
 	may_only_be_test_must_fail "$2" &&
 	$2 git checkout "$1" &&
 	if test -n "$2"
@@ -23,7 +23,7 @@ git_revert () {
 	fi &&
 	git revert HEAD &&
 	rm -rf * &&
-	tar xf "$TRASH_DIRECTORY/tmp.tar" &&
+	"$TAR" xf "$TRASH_DIRECTORY/tmp.tar" &&
 	git status -su >actual &&
 	ls -1pR * >>actual &&
 	test_cmp expect actual &&
diff --git a/t/t6041-bisect-submodule.sh b/t/t6041-bisect-submodule.sh
index df1eff0fb8..82013fc903 100755
--- a/t/t6041-bisect-submodule.sh
+++ b/t/t6041-bisect-submodule.sh
@@ -8,7 +8,7 @@ test_description='bisect can handle submodules'
 git_bisect () {
 	git status -su >expect &&
 	ls -1pR * >>expect &&
-	tar cf "$TRASH_DIRECTORY/tmp.tar" * &&
+	"$TAR" cf "$TRASH_DIRECTORY/tmp.tar" * &&
 	GOOD=$(git rev-parse --verify HEAD) &&
 	may_only_be_test_must_fail "$2" &&
 	$2 git checkout "$1" &&
@@ -25,7 +25,7 @@ git_bisect () {
 	git bisect start &&
 	git bisect good $GOOD &&
 	rm -rf * &&
-	tar xf "$TRASH_DIRECTORY/tmp.tar" &&
+	"$TAR" xf "$TRASH_DIRECTORY/tmp.tar" &&
 	git status -su >actual &&
 	ls -1pR * >>actual &&
 	test_cmp expect actual &&
-- 
2.32.0.rc0.32.g107691cb07