Initialize PSA key slot as invalid in ssl_client2.c
Otherwise, if `mbedtls_psa_get_free_key_slot()` fails to find a fresh
key slot, the slot value will be undefined, and the call to
`psa_destroy_key()` at the end of `main()` is undefined behavior.
diff --git a/programs/ssl/ssl_client2.c b/programs/ssl/ssl_client2.c
index 1bf6e2f..ff625fb 100644
--- a/programs/ssl/ssl_client2.c
+++ b/programs/ssl/ssl_client2.c
@@ -561,7 +561,7 @@
const char *pers = "ssl_client2";
#if defined(MBEDTLS_USE_PSA_CRYPTO)
- psa_key_slot_t slot;
+ psa_key_slot_t slot = 0;
psa_algorithm_t alg = 0;
psa_key_policy_t policy;
psa_status_t status;