don't override libc code in a glibc-specific way when not using glibc

sandbox/linux/services/libc_urandom_override.cc

 // Copyright (c) 2012 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 "sandbox/linux/services/libc_urandom_override.h"
 
 #include <dlfcn.h>
 #include <pthread.h>
 #include <stdio.h>
 #include <sys/stat.h>
@@ skipping 41 matching lines @@
 
   if (!g_libc_fopen) {
     LOG(FATAL) << "Failed to get fopen() from libc.";
   } else if (!g_libc_fopen64) {
 #if !defined(OS_OPENBSD) && !defined(OS_FREEBSD)
     LOG(WARNING) << "Failed to get fopen64() from libc. Using fopen() instead.";
 #endif  // !defined(OS_OPENBSD) && !defined(OS_FREEBSD)
     g_libc_fopen64 = g_libc_fopen;
   }
 
+#if defined(LIBC_GLIBC)
   // TODO(sergeyu): This works only on systems with glibc. Fix it to
   // work properly on other systems if necessary.
   g_libc_xstat = reinterpret_cast<XstatFunction>(
       dlsym(RTLD_NEXT, "__xstat"));
   g_libc_xstat64 = reinterpret_cast<Xstat64Function>(
       dlsym(RTLD_NEXT, "__xstat64"));
 
   if (!g_libc_xstat) {
     LOG(FATAL) << "Failed to get __xstat() from libc.";
   }
@@ skipping 76 matching lines @@
   if (g_override_urandom && strcmp(path, kUrandomDevPath) == 0) {
     int result = __fxstat64(version, base::GetUrandomFD(), buf);
     return result;
   } else {
     CHECK_EQ(0, pthread_once(&g_libc_file_io_funcs_guard,
                              InitLibcFileIOFunctions));
     CHECK(g_libc_xstat64);
     return g_libc_xstat64(version, path, buf);
   }
 }
+#endif  // LIBC_GLIBC

[jln (very slow on Chromium), 2013/06/12 20:27:59]

Nit: this should be "// defined(LIBC_GLIBC)"

[Mostyn Bramley-Moore, 2013/06/12 20:41:41]

That doesn't match the format used two lines down, which has:
// !ADDRESS_SANITIZER

Would you prefer me to change both, or leave both?

 
 #endif  // !ADDRESS_SANITIZER
 
 }  // namespace content