free NULL cleanup

EVP_.*free; this gets:
        EVP_CIPHER_CTX_free EVP_PKEY_CTX_free EVP_PKEY_asn1_free
        EVP_PKEY_asn1_set_free EVP_PKEY_free EVP_PKEY_free_it
        EVP_PKEY_meth_free; and also EVP_CIPHER_CTX_cleanup

Reviewed-by: Kurt Roeckx <kurt@openssl.org>
diff --git a/demos/smime/smsign.c b/demos/smime/smsign.c
index 6b9dfdd..455efcb 100644
--- a/demos/smime/smsign.c
+++ b/demos/smime/smsign.c
@@ -73,8 +73,7 @@
         PKCS7_free(p7);
     if (scert)
         X509_free(scert);
-    if (skey)
-        EVP_PKEY_free(skey);
+    EVP_PKEY_free(skey);
 
     BIO_free(in);
     BIO_free(out);