free NULL cleanup

This commit handles BIO_ACCEPT_free BIO_CB_FREE BIO_CONNECT_free
BIO_free BIO_free_all BIO_vfree

Reviewed-by: Matt Caswell <matt@openssl.org>

demos/smime/smsign.c

diff --git a/demos/smime/smsign.c b/demos/smime/smsign.c
index c7bf86d..6b9dfdd 100644
--- a/demos/smime/smsign.c
+++ b/demos/smime/smsign.c
@@ -76,12 +76,9 @@
     if (skey)
         EVP_PKEY_free(skey);
 
-    if (in)
-        BIO_free(in);
-    if (out)
-        BIO_free(out);
-    if (tbio)
-        BIO_free(tbio);
+    BIO_free(in);
+    BIO_free(out);
+    BIO_free(tbio);
 
     return ret;