tests: Use skip_all=* to skip tests

Change tests to skip with skip_all=* + test_done instead of using say
+ test_done.

This is a follow-up to "tests: Skip tests in a way that makes sense
under TAP" (fadb5156e4). I missed these cases when prepearing that
patch, hopefully this is all of them.

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

t/lib-patch-mode.sh

@@ -3,7 +3,7 @@
 . ./test-lib.sh
 
 if ! test_have_prereq PERL; then
-	say 'skipping --patch tests, perl not available'
+	skip_all='skipping --patch tests, perl not available'
 	test_done
 fi