http_digest: Fixed some memory leaks introduced in commit 6f8d8131

Fixed a couple of memory leaks as a result of moving code that used to
populate allocuserpwd and relied on it's clean up.

lib/curl_sasl.c

@@ -1046,20 +1046,20 @@ CURLcode Curl_sasl_create_digest_http_message(struct SessionHandle *data,
   if(digest->opaque) {
     /* Append the opaque */
     tmp = aprintf("%s, opaque=\"%s\"", response, digest->opaque);
+    free(response);
     if(!tmp)
       return CURLE_OUT_OF_MEMORY;
 
-    free(response);
     response = tmp;
   }
 
   if(digest->algorithm) {
     /* Append the algorithm */
     tmp = aprintf("%s, algorithm=\"%s\"", response, digest->algorithm);
+    free(response);
     if(!tmp)
       return CURLE_OUT_OF_MEMORY;
 
-    free(response);
     response = tmp;
   }