t4210: skip more command-line encoding tests on MinGW

In 5212f91deb ("t4210: skip command-line encoding tests on mingw",
2014-07-17) the positive tests in this file were skipped. That left
the negative tests that don't produce a match.

An upcoming change to migrate the "fixed" backend of grep to PCRE v2
will cause these "log" commands to produce an error instead on
MinGW. This is because the command-line on that platform implicitly
has its encoding changed before being passed to git. See [1].

1. https://public-inbox.org/git/nycvar.QRO.7.76.6.1907011515150.44@tvgsbejvaqbjf.bet/

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

t/t4210-log-i18n.sh

@@ -51,7 +51,7 @@ test_expect_success !MINGW 'log --grep does not find non-reencoded values (utf8)
 	test_must_be_empty actual
 '
 
-test_expect_success 'log --grep does not find non-reencoded values (latin1)' '
+test_expect_success !MINGW 'log --grep does not find non-reencoded values (latin1)' '
 	git log --encoding=ISO-8859-1 --format=%s --grep=$utf8_e >actual &&
 	test_must_be_empty actual
 '
@@ -70,7 +70,7 @@ do
 	then
 	    force_regex=.*
 	fi
-	test_expect_success GETTEXT_LOCALE,$prereq "-c grep.patternType=$engine log --grep does not find non-reencoded values (latin1 + locale)" "
+	test_expect_success !MINGW,GETTEXT_LOCALE,$prereq "-c grep.patternType=$engine log --grep does not find non-reencoded values (latin1 + locale)" "
 		cat >expect <<-\EOF &&
 		latin1
 		utf8
@@ -79,12 +79,12 @@ do
 		test_cmp expect actual
 	"
 
-	test_expect_success GETTEXT_LOCALE,$prereq "-c grep.patternType=$engine log --grep does not find non-reencoded values (latin1 + locale)" "
+	test_expect_success !MINGW,GETTEXT_LOCALE,$prereq "-c grep.patternType=$engine log --grep does not find non-reencoded values (latin1 + locale)" "
 		LC_ALL=\"$is_IS_locale\" git -c grep.patternType=$engine log --encoding=ISO-8859-1 --format=%s --grep=\"$force_regex$utf8_e\" >actual &&
 		test_must_be_empty actual
 	"
 
-	test_expect_success GETTEXT_LOCALE,$prereq "-c grep.patternType=$engine log --grep does not die on invalid UTF-8 value (latin1 + locale + invalid needle)" "
+	test_expect_success !MINGW,GETTEXT_LOCALE,$prereq "-c grep.patternType=$engine log --grep does not die on invalid UTF-8 value (latin1 + locale + invalid needle)" "
 		LC_ALL=\"$is_IS_locale\" git -c grep.patternType=$engine log --encoding=ISO-8859-1 --format=%s --grep=\"$force_regex$invalid_e\" >actual &&
 		test_must_be_empty actual
 	"