[MIPS] Add remaining parts for building tests for MIPS

tests/stack_alignment/stack_alignment_asm_test.c

 /*
  * Copyright (c) 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 <assert.h>
 #include <sched.h>
 #include <stdint.h>
 #include <stdio.h>
@@ skipping 42 matching lines @@
     ".pushsection .text, \"ax\", %progbits\n"
     "ThreadStartWrapper:\n"
     "mov r0, sp\n"  /* Set argument */
     "nop; nop\n"  /* Padding to put the "bl" at the end of the bundle */
     "bl ThreadStart\n"
     ".popsection\n");
 
 static const int kStackAlignment = 8;
 static const int kStackPadBelowAlign = 0;
 
+#elif defined(__mips__)
+
+__asm__(
+    ".pushsection .text, \"ax\", %progbits\n"
+    "ThreadStartWrapper:\n"
+    "move $a0, $sp\n"  /* Set argument. */
+    "nop\n"
+    "bal ThreadStart\n"
+    "nop\n"
+    ".popsection\n");
+
+static const int kStackAlignment = 8;
+static const int kStackPadBelowAlign = 0;
+
 #else
 # error Unsupported architecture
 #endif
 
 void ThreadStartWrapper(void);
 
 void ThreadStart(char *stack_ptr) {
   /*
    * We do not have TLS set up in this thread, so we don't use libc
    * functions like assert() here.  Instead, we save stack_ptr and let
@@ skipping 21 matching lines @@
       sched_yield();
     }
     printf("got g_stack_ptr=%p\n", g_stack_ptr);
     assert(g_stack_ptr <= stack_top);
     assert(((uintptr_t) g_stack_ptr + kStackPadBelowAlign) % kStackAlignment
            == 0);
   }
 
   return 0;
 }