[MIPS] Use break instruction as NACL_HALT for MIPS.

src/trusted/service_runtime/arch/mips/sel_ldr_mips.h

 /*
  * Copyright 2012 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 SERVICE_RUNTIME_ARCH_MIPS_SEL_LDR_H__
 #define SERVICE_RUNTIME_ARCH_MIPS_SEL_LDR_H__ 1
 
-#include "native_client/src/include/portability.h"
+#if !defined(__ASSEMBLER__)
+# include "native_client/src/include/portability.h"
+#endif
+
 #include "native_client/src/trusted/service_runtime/nacl_config.h"
 
 #define NACL_MAX_ADDR_BITS      30
 
 #define NACL_ADDRSPACE_LOWER_GUARD_SIZE 0
 #define NACL_ADDRSPACE_UPPER_GUARD_SIZE 0x2000
 
 /* Must be synced with irt_compatible_rodata_addr in SConstruct */
 #define NACL_DATA_SEGMENT_START 0x10000000
 
 #define NACL_THREAD_MAX         8192
 
 #define NACL_NOOP_OPCODE        0x00000000  /* nop */
-#define NACL_HALT_OPCODE        0x00000008  /* jr $0 */
+#define NACL_HALT_OPCODE        0x0000000D  /* break */
 #define NACL_HALT_LEN           4           /* length of halt instruction */
 #define NACL_HALT_WORD          NACL_HALT_OPCODE
 
 #endif /* SERVICE_RUNTIME_ARCH_MIPS_SEL_LDR_H__ */