Only run "Default" tests if the ciphersuite is enabled

These tests ensure that a certain cipher suite is in use, so they fail in
builds that lack one of the corresponding algorithms.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index 8833830..0d79ae5 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -1385,6 +1385,7 @@
 # - the expected (highest security) parameters are selected
 #   ("signature_algorithm ext: 6" means SHA-512 (highest common hash))
 requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_2
+requires_ciphersuite_enabled TLS-ECDHE-RSA-WITH-CHACHA20-POLY1305-SHA256
 run_test    "Default" \
             "$P_SRV debug_level=3" \
             "$P_CLI" \
@@ -1397,6 +1398,7 @@
             -C "error"
 
 requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_2
+requires_ciphersuite_enabled TLS-ECDHE-RSA-WITH-CHACHA20-POLY1305-SHA256
 run_test    "Default, DTLS" \
             "$P_SRV dtls=1" \
             "$P_CLI dtls=1" \