move libevent into base

base/third_party/libevent/evutil.c

 /*
  * Copyright (c) 2007 Niels Provos <provos@citi.umich.edu>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 264 matching lines @@
 }
 
 const char *
 evutil_getenv(const char *varname)
 {
         if (evutil_issetugid())
                 return NULL;
 
         return getenv(varname);
 }