[NaCl SDK] Enable linux host build for nacl_io and nacl_io_tests.

native_client_sdk/src/libraries/nacl_io/mount_dev.cc

 // Copyright (c) 2013 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.
 
 #if defined(WIN32)
 #define _CRT_RAND_S
 #endif
 
 #include <errno.h>
 #include <fcntl.h>
@@ skipping 210 matching lines @@
   *out_bytes = 0;
 
 #if defined(__native_client__)
   if (!interface_ok_)
     return EBADF;
 
   size_t nread;
   int error = (*random_interface_.get_random_bytes)(buf, count, &nread);
   if (error)
     return error;
-
-  *out_bytes = count;
-  return 0;
 #elif defined(WIN32)
   char* out = static_cast<char*>(buf);
   size_t bytes_left = count;
   while (bytes_left) {
     unsigned int random_int;
     errno_t err = rand_s(&random_int);
     if (err) {
       *out_bytes = count - bytes_left;
       return err;
     }
 
     int bytes_to_copy = std::min(bytes_left, sizeof(random_int));
     memcpy(out, &random_int, bytes_to_copy);
     out += bytes_to_copy;
     bytes_left -= bytes_to_copy;
   }
+#endif
 
   *out_bytes = count;
   return 0;
-#endif
 }
 
 Error UrandomNode::Write(const HandleAttr& attr,
                          const void* buf,
                          size_t count,
                          int* out_bytes) {
   *out_bytes = count;
   return 0;
 }
 
@@ skipping 63 matching lines @@
   INITIALIZE_DEV_NODE("/tty", MountNodeTty);
   INITIALIZE_DEV_NODE_1("/stdin", RealNode, 0);
   INITIALIZE_DEV_NODE_1("/stdout", RealNode, 1);
   INITIALIZE_DEV_NODE_1("/stderr", RealNode, 2);
 
   return 0;
 }
 
 }  // namespace nacl_io