title: How to add external header files during bazel/tensorflow build
body: <p>I am trying to add external header file (like OpenCL header file) for some experimentation for tensorflow. I tried to add this into BUILD file under tensorflow/core/BUILD file:</p>
  
  <pre><code># This includes implementations of all kernels built into TensorFlow.
  cc_library(
      name = "all_kernels",
      visibility = ["//visibility:public"],
      copts = tf_copts() + ["-Ithird_party/include"],    &lt;==== this is the line I added
  </code></pre>
  
  <p>I have also created a softlink in this directory to the location of these header files from OpenCL driver (under tensorflow/third_party) too (like ln -s /opt/opencl/ ) but it still complains that it has not found that header file.</p>
  
  <p>If I add external header file directly (like /opt/opencl/CL/) it complains that external files cannot be included (or some such thing). </p>
  
  <p>I do not have root password to copy these header files into /usr/include/ too.</p>
  
  <p>Can someone explain how exactly to do external header files into tensorflow for building?</p>
  
  <p>Thanks for any quick help.</p>