Change BKPT and UDF encodings on ARM.

tests/syscall_return_sandboxing/sandboxed_arm.S

Index: tests/syscall_return_sandboxing/sandboxed_arm.S
diff --git a/tests/syscall_return_sandboxing/sandboxed_arm.S b/tests/syscall_return_sandboxing/sandboxed_arm.S
index 9daaaa5be137e5323f895d7b3420941ff24fdf86..bdb866b6c5c3d752b4ad48f161356977cf877db3 100644
--- a/tests/syscall_return_sandboxing/sandboxed_arm.S
+++ b/tests/syscall_return_sandboxing/sandboxed_arm.S
@@ -4,6 +4,8 @@
  * be found in the LICENSE file.
  */
 
+#include "native_client/src/include/arm_sandbox.h"
+
         /*
          * assume 32-byte trampoline slots, 16-byte bundles.
          */
@@ -32,7 +34,7 @@ bad:    pop {lr}
         bx lr
 
 
-        bkpt 0x7777
+        .word NACL_INSTR_LITERAL_POOL_HEAD
         /*
          * Put a disallowed instruction here to ensure that the bkpt
          * data bundle marker works.  If the marker does not work, then