Ensure syscall functions are consistently prefixed with "NaClSys"

src/trusted/service_runtime/arch/mips/nacl_text_pad_test.S

 /*
  * 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.
  */
 
 #include "native_client/src/trusted/service_runtime/arch/mips/sel_ldr_mips.h"
 #include "native_client/src/trusted/service_runtime/include/bits/nacl_syscalls.h"
 #include "native_client/src/trusted/service_runtime/nacl_config.h"
 
@@ skipping 119 matching lines @@
         addiu $a1, $a1, %lo(end_of_text)
         jal   write_num_16
         addu  $a0, $zero, 1
 
         addu  $a0, $zero, 1
         addu  $a1, $zero, '\n'
         jal   write_char
         nop
 
         addu  $a0, $zero, 0
-        lui   $t9, %hi(NACL_SYSCALL_ADDR(NACL_sys_sysbrk))
-        addiu $t9, $t9, %lo(NACL_SYSCALL_ADDR(NACL_sys_sysbrk))
+        lui   $t9, %hi(NACL_SYSCALL_ADDR(NACL_sys_brk))
+        addiu $t9, $t9, %lo(NACL_SYSCALL_ADDR(NACL_sys_brk))
         nop
 
         nop
         and   $t9, $t9, JUMP_MASK
         jalr  $t9
         nop
 
         move  $s0, $v0                     /* save a copy of break addr */
         move  $a1, $v0
         jal   write_num_16
@@ skipping 93 matching lines @@
         .fill (TEXT_EXTEND - (. - start_of_text))/4, 4, NACL_HALT_OPCODE
 #endif
 
 end_of_text:
 
 #if defined(EXPECTED_RODATA)
         .section .rodata
 ro_str: .ascii "Hello world\n"
 #endif