t4016-*.sh: Skip all tests rather than each test

Each test in this file is skipped if the TABS_IN_FILENAMES test
prerequisite is set. Use the 'skip_all' facility at the head of
the file to skip all of the tests instead.

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t4016-diff-quote.sh

@@ -13,14 +13,12 @@ P1='pathname	with HT'
 P2='pathname with SP'
 P3='pathname
 with LF'
-if : 2>/dev/null >"$P1" && test -f "$P1" && rm -f "$P1"
-then
-	test_set_prereq TABS_IN_FILENAMES
-else
-	say 'Your filesystem does not allow tabs in filenames'
-fi
+echo 2>/dev/null >"$P1" && test -f "$P1" && rm -f "$P1" || {
+	skip_all='Your filesystem does not allow tabs in filenames'
+	test_done
+}
 
-test_expect_success TABS_IN_FILENAMES setup '
+test_expect_success setup '
 	echo P0.0 >"$P0.0" &&
 	echo P0.1 >"$P0.1" &&
 	echo P0.2 >"$P0.2" &&
@@ -40,7 +38,7 @@ test_expect_success TABS_IN_FILENAMES setup '
 	:
 '
 
-test_expect_success TABS_IN_FILENAMES 'setup expected files' '
+test_expect_success 'setup expected files' '
 cat >expect <<\EOF
  rename pathname.1 => "Rpathname\twith HT.0" (100%)
  rename pathname.3 => "Rpathname\nwith LF.0" (100%)
@@ -52,12 +50,12 @@ cat >expect <<\EOF
 EOF
 '
 
-test_expect_success TABS_IN_FILENAMES 'git diff --summary -M HEAD' '
+test_expect_success 'git diff --summary -M HEAD' '
 	git diff --summary -M HEAD >actual &&
 	test_cmp expect actual
 '
 
-test_expect_success TABS_IN_FILENAMES 'git diff --numstat -M HEAD' '
+test_expect_success 'git diff --numstat -M HEAD' '
 	cat >expect <<-\EOF &&
 	0	0	pathname.1 => "Rpathname\twith HT.0"
 	0	0	pathname.3 => "Rpathname\nwith LF.0"
@@ -71,7 +69,7 @@ test_expect_success TABS_IN_FILENAMES 'git diff --numstat -M HEAD' '
 	test_cmp expect actual
 '
 
-test_expect_success TABS_IN_FILENAMES 'git diff --stat -M HEAD' '
+test_expect_success 'git diff --stat -M HEAD' '
 	cat >expect <<-\EOF &&
 	 pathname.1 => "Rpathname\twith HT.0"            | 0
 	 pathname.3 => "Rpathname\nwith LF.0"            | 0