Enable tcmalloc VDSO support only on x86 to reduce static initializers

third_party/tcmalloc/chromium/src/base/vdso_support.h

 // Copyright (c) 2008, Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
@@ skipping 43 matching lines @@
 
 #ifndef BASE_VDSO_SUPPORT_H_
 #define BASE_VDSO_SUPPORT_H_
 
 #include <config.h>
 #include "base/basictypes.h"
 #include "base/elf_mem_image.h"
 
 #ifdef HAVE_ELF_MEM_IMAGE
 
+// This matches the same conditions of stacktrace_x86-inl.h, the only client of
+// vdso_support, to avoid static initializers.
+#if defined(__linux__) && defined(__i386__)
 #define HAVE_VDSO_SUPPORT 1
+#endif
 
 #include <stdlib.h>     // for NULL
 
 namespace base {
 
 // NOTE: this class may be used from within tcmalloc, and can not
 // use any memory allocation routines.
 class VDSOSupport {
  public:
   VDSOSupport();
@@ skipping 71 matching lines @@
 // Return current CPU, using (fast) __vdso_getcpu@LINUX_2.6 if present,
 // otherwise use syscall(SYS_getcpu,...).
 // May return -1 with errno == ENOSYS if the kernel doesn't
 // support SYS_getcpu.
 int GetCPU();
 }  // namespace base
 
 #endif  // HAVE_ELF_MEM_IMAGE
 
 #endif  // BASE_VDSO_SUPPORT_H_