Non-SFI mode: Add Linux asynchronous signal support

src/public/nonsfi/irt_signal_handling.h

Index: src/public/nonsfi/irt_signal_handling.h
diff --git a/src/public/nonsfi/irt_signal_handling.h b/src/public/nonsfi/irt_signal_handling.h
new file mode 100644
index 0000000000000000000000000000000000000000..7ae34d5b803ec8f7ef45a4dfa6ac745a7e217e39
--- /dev/null
+++ b/src/public/nonsfi/irt_signal_handling.h
@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2015 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.
+ */
+
+#ifndef NATIVE_CLIENT_SRC_PUBLIC_NONSFI_IRT_SIGNAL_HANDLING_H_
+#define NATIVE_CLIENT_SRC_PUBLIC_NONSFI_IRT_SIGNAL_HANDLING_H_ 1
+
+#include "native_client/src/include/nacl_base.h"
+
+EXTERN_C_BEGIN
+
+/* Initialize signal handler for exceptions and regular signals at startup

[Mark Seaborn, 2015/06/26 18:31:59]

Nit: Use the NaCl style for multiline comments, with "/*" and "*/" on separate
lines, like this:
/*
 * Blah...
 * blah.
 */

[Luis Héctor Chávez, 2015/07/06 23:45:00]

Done.

+ * before entering sandbox. */
+void nonsfi_initialize_signal_handler(void);
+
+EXTERN_C_END
+
+#endif