easy: Fixed a memory leak on OOM condition

lib/easy.c

@@ -715,6 +715,15 @@ static CURLcode easy_transfer(CURLM *multi)
       }
     }
   }
+
+  /* Make sure to return some kind of error if there was a multi problem */
+  if(mcode) {
+    return (mcode == CURLM_OUT_OF_MEMORY) ? CURLE_OUT_OF_MEMORY :
+            /* The other multi errors should never happen, so return
+               something suitably generic */
+            CURLE_BAD_FUNCTION_ARGUMENT;
+  }
+
   return code;
 }