compat.sh: include ssl3 in --list-test-cases

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/tests/compat.sh b/tests/compat.sh
index 03e7298..64c67ce 100755
--- a/tests/compat.sh
+++ b/tests/compat.sh
@@ -138,6 +138,9 @@
     EXCLUDE='^$'
     FILTER=""
 
+    # ssl3 is excluded by default, but it's still available
+    MODES="ssl3 $MODES"
+
     for MODE in $MODES; do
         for TYPE in $TYPES; do
             # PSK cipher suites do not allow client certificate verification.