Add comments to some endif guards

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/programs/ssl/ssl_client2.c b/programs/ssl/ssl_client2.c
index 56df7df..876555d 100644
--- a/programs/ssl/ssl_client2.c
+++ b/programs/ssl/ssl_client2.c
@@ -762,8 +762,8 @@
     }
 #if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
     mbedtls_test_enable_insecure_external_rng( );
-#endif
-#endif
+#endif  /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
+#endif  /* MBEDTLS_USE_PSA_CRYPTO */
 
     if( argc == 0 )
     {