Reland "Non-SFI mode: Add Linux asynchronous signal support"

src/nonsfi/linux/irt_signal_handling.h

Index: src/nonsfi/linux/irt_signal_handling.h
diff --git a/src/nonsfi/linux/irt_signal_handling.h b/src/nonsfi/linux/irt_signal_handling.h
new file mode 100644
index 0000000000000000000000000000000000000000..eff45af24144dd0ed115662a6b89af476b8da7a9
--- /dev/null
+++ b/src/nonsfi/linux/irt_signal_handling.h
@@ -0,0 +1,23 @@
+/*
+ * 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_NONSFI_LINUX_IRT_SIGNAL_HANDLING_H_
+#define NATIVE_CLIENT_SRC_NONSFI_LINUX_IRT_SIGNAL_HANDLING_H_ 1
+
+#include "native_client/src/untrusted/irt/irt.h"
+
+EXTERN_C_BEGIN
+
+/*
+ * See documentation for nacl_irt_async_signal_handler members in
+ * src/untrusted/irt/irt.h
+ */
+int nacl_async_signal_set_handler(NaClIrtAsyncSignalHandler handler);
+int nacl_async_signal_send_async_signal(nacl_irt_tid_t tid);
+
+EXTERN_C_END
+
+#endif