[newlib-cygwin] Add a dummy interrupt handler to nios2 crt0.s.

[Corinna Vinschen <corinna@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=c4c614046308a55e4b478c3609f05101c1b8e6b6

commit c4c614046308a55e4b478c3609f05101c1b8e6b6
Author: Sandra Loosemore <sandra@codesourcery.com>
Date:   Wed Apr 3 09:59:36 2019 -0600

    Add a dummy interrupt handler to nios2 crt0.s.
    
    The location of the handler at offset 0x20 from the start of memory,
    immediately after the 32-byte reset vector, matches the expectations
    of real hardware (e.g., a 3c120 board).

Diff:
---
 libgloss/nios2/crt0.S | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/libgloss/nios2/crt0.S b/libgloss/nios2/crt0.S
index 77eacb3..c4dd4c6 100644
--- a/libgloss/nios2/crt0.S
+++ b/libgloss/nios2/crt0.S
@@ -1,6 +1,6 @@
 /* crt0.S -- startup code for Nios II QEMU generic-nommu board emulation.
 
-   Copyright (c) 2018 Mentor Graphics
+   Copyright (c) 2018-2019 Mentor Graphics
 
    The authors hereby grant permission to use, copy, modify, distribute,
    and license this software and its documentation for any purpose, provided
@@ -81,6 +81,18 @@ __reset:
 
 	.size __reset, . - __reset
 
+/* Provide a stub interrupt handler that waits in a busy loop.
+   The alignment puts it at offset 0x20 from the base of RAM.  */
+
+	.align 5
+
+        .globl  __interrupt_handler
+        .type   __interrupt_handler, @function
+__interrupt_handler:
+0:
+	br 0b
+
+	.size __interrupt_handler, . - __interrupt_handler
 
 /* __start is the ELF entry point.  */