Remove LTO-related hacks from binutils build script.

This effectively reverts:
https://codereview.chromium.org/1330433002 (link against LLVM's libstdc++)
https://codereview.chromium.org/1670073003 (link against tcmalloc)
and part of https://codereview.chromium.org/899783003 (export plugin-api.h)

All of which were to support use of LLVM's gold plugin for LTO.
Because we no longer build or use the gold plugin, we no longer need
this complexity in the build script.

BUG=607968
R=thakis@chromium.org

Review-Url: https://codereview.chromium.org/2961943002
Cr-Original-Commit-Position: refs/heads/master@{#483173}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: effae3bbe9479ad36042df4b4a5db3dc3ebf0c41
5 files changed