[MIPS] Add support for thread_suspension test

[MIPS] Add support for thread_suspension test

This change:

- implements NaClSignalContextUnsetClobberedRegisters() for MIPS,
- modifies Unwind for thread suspension to match what is needed for MIPS,
- adds MIPS-arch specific parts in suspend_test_guest.c and
  suspend_test_host.c.

BUG= run_thread_suspension_test fails for MIPS
TEST= run run_thread_suspension_test on MIPS-board

Committed: http://src.chromium.org/viewvc/native_client?view=rev&revision=12571

[petarj, 2013-12-27 20:14:23]

PTAL.

[Mark Seaborn, 2013-12-27 21:09:16]

LGTM.  I would recommend enabling tests/signal_handler_single_step/ for MIPS as
well.  tests/thread_suspension's testing of suspending in the middle of a
context switch (the unwinding part) is only a stress test, whereas
signal_handler_single_step will step through each instruction.

https://chromiumcodereview.appspot.com/121833002/diff/1/tests/thread_suspensi...
File tests/thread_suspension/suspend_test_host.c (right):

https://chromiumcodereview.appspot.com/121833002/diff/1/tests/thread_suspensi...
tests/thread_suspension/suspend_test_host.c:343: /* Skip setting zero register
because it's read-only. */ \
Can you remove the backslashes from these comments?

[petarj, 2013-12-27 23:03:35]

https://chromiumcodereview.appspot.com/121833002/diff/1/tests/thread_suspensi...
File tests/thread_suspension/suspend_test_host.c (right):

https://chromiumcodereview.appspot.com/121833002/diff/1/tests/thread_suspensi...
tests/thread_suspension/suspend_test_host.c:343: /* Skip setting zero register
because it's read-only. */ \
On 2013/12/27 21:09:16, Mark Seaborn wrote:
> Can you remove the backslashes from these comments?

Done.

[commit-bot: I haz the power, 2013-12-27 23:04:03]

CQ is trying da patch. Follow status at
https://nativeclient-status.appspot.com/cq/petarj@mips.com/121833002/240001

[commit-bot: I haz the power, 2013-12-28 00:32:09]

Change committed as 12571