test-parse-options: update to handle negative ints

Fix the printf specification to treat 'integer' as the signed type
that it is and add a test that checks that we parse negative option
arguments.

Signed-off-by: Charles Bailey <cbailey32@bloomberg.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t0040-parse-options.sh

@@ -132,6 +132,8 @@ test_expect_success 'OPT_BOOL() no negation #2' 'check_unknown_i18n --no-no-fear
 
 test_expect_success 'OPT_BOOL() positivation' 'check boolean: 0 -D --doubt'
 
+test_expect_success 'OPT_INT() negative' 'check integer: -2345 -i -2345'
+
 cat > expect << EOF
 boolean: 2
 integer: 1729