Use p==NULL not !p (in if statements, mainly)

Reviewed-by: Tim Hudson <tjh@openssl.org>
diff --git a/apps/x509.c b/apps/x509.c
index 5938b43..f22eef1 100644
--- a/apps/x509.c
+++ b/apps/x509.c
@@ -1021,11 +1021,9 @@
     }
     if (sno)
         bs = sno;
-    else if (!(bs = x509_load_serial(CAfile, serialfile, create)))
+    else if ((bs = x509_load_serial(CAfile, serialfile, create)) == NULL)
         goto end;
 
-/*      if (!X509_STORE_add_cert(ctx,x)) goto end;*/
-
     /*
      * NOTE: this certificate can/should be self signed, unless it was a
      * certificate request in which case it is not.