Exit with -sig when handling signals.

src/nonsfi/linux/irt_exception_handling.c

 /*
  * Copyright (c) 2014 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include <errno.h>
 #include <pthread.h>
 #include <signal.h>
 #include <stdint.h>
@@ skipping 178 matching lines @@
 #endif
 }
 
 /* Signal handler, responsible for calling the registered handler. */
 static void signal_catch(int sig, linux_siginfo_t *info, void *uc) {
   if (g_signal_handler_function_pointer) {
     struct NonSfiExceptionFrame exception_frame;
     exception_frame_from_signal_context(&exception_frame, uc);
     g_signal_handler_function_pointer(&exception_frame.context);
   }
-  _exit(-1);
+  _exit(-sig);
 }
 
 static void nonsfi_initialize_signal_handler_locked() {
   struct linux_sigaction sa;
   unsigned int a;
 
   memset(&sa, 0, sizeof(sa));
   sa.sa_sigaction = signal_catch;
   sa.sa_flags = LINUX_SA_SIGINFO | LINUX_SA_ONSTACK;
 
@@ skipping 76 matching lines @@
   if (linux_sigprocmask(LINUX_SIG_UNBLOCK, &mask, NULL) != 0)
     abort();
 
   return 0;
 }
 
 int nacl_exception_set_stack(void *p, size_t s) {
   /* Not implemented yet. */
   return ENOSYS;
 }