Revert 47897 - Linux: Add libunwind as a dependency of tcmalloc in 64 bit mode.

Based on willchan's patch here: http://codereview.chromium.org/2109009/show

BUG=40149
TEST=none
TBR=willchan
Review URL: http://codereview.chromium.org/2137010

TBR=thestig@chromium.org
Review URL: http://codereview.chromium.org/2107016

git-svn-id: http://src.chromium.org/svn/trunk/src/build@47933 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

all.gyp

@@ -1,4 +1,4 @@
-# Copyright (c) 2010 The Chromium Authors. All rights reserved.
+# Copyright (c) 2009 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.
 
@@ -83,13 +83,6 @@
             '../tools/xdisplaycheck/xdisplaycheck.gyp:*',
             '../net/third_party/nss/nss.gyp:*',
           ],
-          'conditions': [
-            ['target_arch=="x64"', {
-              'dependencies': [
-                '../third_party/libunwind/libunwind.gyp:*',
-              ],
-            }],
-          ],
         }],
         ['OS=="win"', {
           'conditions': [