Enable tcmalloc VDSO support only on x86 to reduce static initializers

base/allocator/BUILD.gn

 # 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.
 
 import("//build/config/allocator.gni")
 import("//build/config/compiler/compiler.gni")
 
 if (is_win) {
   import("//build/config/win/visual_studio_version.gni")
 }
@@ skipping 100 matching lines @@
       deps = [
         ":prep_libc",
         "//base",
       ]
     }
   }
 }
 
 if (use_allocator == "tcmalloc") {
   # tcmalloc currently won't compile on Android.
-  # TODO(crbug.com/559766) this should be a source_set but
-  # there are static initializers that get accidentally linked
-  # into chrome from vdso_support.cc that need to be addressed first.
-  static_library("tcmalloc") {
+  source_set("tcmalloc") {
     tcmalloc_dir = "//third_party/tcmalloc/chromium"
 
     # Don't check tcmalloc's includes. These files include various files like
     # base/foo.h and they actually refer to tcmalloc's forked copy of base
     # rather than the regular one, which confuses the header checker.
     check_includes = false
 
     sources = [
       # Generated for our configuration from tcmalloc's build
       # and checked in.
@@ skipping 150 matching lines @@
 
     # Make sure the allocation library is optimized as much as possible when
     # we"re in release mode.
     if (!is_debug) {
       configs -= [ "//build/config/compiler:default_optimization" ]
       configs += [ "//build/config/compiler:optimize_max" ]
     }
 
     deps += [ "//base/third_party/dynamic_annotations" ]
   }
-}  # !is_android
+}  # use_allocator == "tcmalloc"