t5000: silence unzip availability check

unzip -v on (at least) Ubuntu prints a screenful of version info
to stdout.  Get rid of it since we only want to know if unzip is
installed or not.

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>

t/t5000-tar-tree.sh

@@ -108,7 +108,7 @@ test_expect_success \
     'git-archive --format=zip' \
     'git-archive --format=zip HEAD >d.zip'
 
-$UNZIP -v 2>/dev/null
+$UNZIP -v >/dev/null 2>&1
 if [ $? -eq 127 ]; then
 	echo "Skipping ZIP tests, because unzip was not found"
 	test_done