Pass "\$ORIGIN" to ROCm crosstool to preserve "$ORIGIN" at link time

This commit removes LD_LIBRARY_PATH env var previously required on ROCm
platform.

Further commit need to improve logic here so it's only applied when
TensorFlow is configured to be built on ROCm platform. Right now the commit applies to all environments.

Author: whchung

build

@@ -9,6 +9,6 @@
 # press enter all the way
 #
 pip3 uninstall -y tensorflow || true
-LD_LIBRARY_PATH=~/.cache/bazel/_bazel_root/efb88f6336d9c4a18216fb94287b8d97/execroot/org_tensorflow/bazel-out/host/bin/tensorflow bazel build --config=opt --config=rocm //tensorflow/tools/pip_package:build_pip_package --verbose_failures &&
+bazel build --config=opt --config=rocm //tensorflow/tools/pip_package:build_pip_package --verbose_failures &&
 bazel-bin/tensorflow/tools/pip_package/build_pip_package /tmp/tensorflow_pkg &&
 pip3 install /tmp/tensorflow_pkg/tensorflow-1.8.0rc1-cp35-cp35m-linux_x86_64.whl

tensorflow/tensorflow.bzl

@@ -284,7 +284,7 @@ def _rpath_linkopts(name):
       clean_dep("//tensorflow:windows"): [],
       clean_dep("//tensorflow:windows_msvc"): [],
       "//conditions:default": [
-          "-Wl,%s" % (_make_search_paths("$$ORIGIN", levels_to_root),),
+          "-Wl,%s" % (_make_search_paths("\\\$$ORIGIN", levels_to_root),),
       ],
   })