Allow the seccomp sandbox to be enabled, even if the suid sandbox has...

sandbox/linux/seccomp/exit.cc

 #include "debug.h"
 #include "sandbox_impl.h"
 
 namespace playground {
 
 int Sandbox::sandbox_exit(int status) {
   Debug::syscall(__NR_exit, "Executing handler");
   struct {
     int       sysnum;
     long long cookie;
   } __attribute__((packed)) request;
   request.sysnum = __NR_exit;
   request.cookie = cookie();
 
   SysCalls sys;
   if (write(sys, processFdPub(), &request, sizeof(request)) !=
       sizeof(request)) {
     die("Failed to forward exit() request [sandbox]");
   }
   for (;;) {
     sys._exit(status);
   }
 }
 
-bool Sandbox::process_exit(int parentProc, int sandboxFd, int threadFdPub,
+bool Sandbox::process_exit(int parentMapsFd, int sandboxFd, int threadFdPub,
                            int threadFd, SecureMem::Args* mem) {
-  SecureMem::lockSystemCall(parentProc, mem);
-  SecureMem::sendSystemCall(threadFdPub, true, parentProc, mem, __NR_exit, 0);
+  SecureMem::lockSystemCall(parentMapsFd, mem);
+  SecureMem::sendSystemCall(threadFdPub, true, parentMapsFd, mem,
+                            __NR_exit, 0);
   return true;
 }
 
 } // namespace