- clearenv(3) is a GNU extension

--- usertable.cpp.orig	Sat Apr  7 00:19:27 2012
+++ usertable.cpp	Wed Apr 27 11:01:00 2016
@@ -545,8 +545,8 @@ void UserTable::RunAsUser(char* const* argv) const
   }
 
   if (pwd->pw_uid != 0) {
-    if (clearenv() != 0)
-      goto failed;
+    extern char **environ;
+    environ = (char **)calloc(1, sizeof(*environ));
 
     if (    setenv("LOGNAME",   pwd->pw_name,   1) != 0
         ||  setenv("USER",      pwd->pw_name,   1) != 0