Prevent compiling cpu_unittest on i386....

base/cpu_unittest.cc

 // Copyright (c) 2011 The Chromium 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 "base/cpu.h"
 
 #include "testing/gtest/include/gtest/gtest.h"
 
 // Tests whether we can run extended instructions represented by the CPU
 // information. This test actually executes some extended instructions (such as
@@ skipping 33 matching lines @@
 
   if (cpu.has_sse41()) {
     // Execute an SSE 4.1 instruction.
     __asm pmuldq xmm0, xmm0;
   }
 
   if (cpu.has_sse42()) {
     // Execute an SSE 4.2 instruction.
     __asm crc32 eax, eax;
   }
-#elif defined(OS_POSIX)
+#elif defined(OS_POSIX) || defined(__x86_64__)
   ASSERT_TRUE(cpu.has_mmx());
 
   // Execute an MMX instruction.
   __asm__ __volatile__("emms\n" : : : "mm0");
 
   if (cpu.has_sse()) {
     // Execute an SSE instruction.
     __asm__ __volatile__("xorps %%xmm0, %%xmm0\n" : : : "xmm0");
   }
 
@@ skipping 17 matching lines @@
     __asm__ __volatile__("pmuldq %%xmm0, %%xmm0\n" : : : "xmm0");
   }
 
   if (cpu.has_sse42()) {
     // Execute an SSE 4.2 instruction.
     __asm__ __volatile__("crc32 %%eax, %%eax\n" : : : "eax");
   }
 #endif
 #endif
 }