TCMalloc: don't use initialize hook.  Just set the hook pointers directly.
TCMalloc: don't use initialize hook.  Just set the hook pointers directly.

Don't do this for memalign since it's already done elsewhere.
TODO(willchan): Mimic MemalignOverride and get it working for debugallocation and HeapChecker later.

BUG=40974,42171

Review URL: http://codereview.chromium.org/1693003

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@45197 0039d316-1c4b-4281-b951-d872f2087c98

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