title: pkg_config_path error on building with docker
body: <p><strong>When I am building an image for my Go application through docker, I am getting the following error:</strong></p>
  <p><strong># pkg-config --cflags oci8</strong></p>
  <p>Package oci8 was not found in the pkg-config search path.
  Perhaps you should add the directory containing `oci8.pc'
  to the PKG_CONFIG_PATH environment variable
  No package 'oci8' found
  pkg-config: exit status 1</p>
  <p>I have set the environment variable in my Dockerfile also. But still the issue persists.
  My Dockerfile is:</p>
  <pre><code>*FROM golang:1.9
  ARG app_env
  ENV APP_ENV $app_env
  ENV GOPATH /home/nupur/mapi-go
  ENV PKG_CONFIG_PATH /home/nupur/mapi-go
  ENV ORACLE_HOME /usr/include/oracle/11.2/client64
  ENV LD_LIBRARY_PATH /usr/lib/oracle/11.2/client64/lib
  WORKDIR /home/nupur/mapi-go/src/DockerApp/blDocker
  ADD . .
  RUN go build /home/nupur/mapi-go/src/DockerApp/blDocker/launch.go
  ENTRYPOINT [&quot;./launch&quot;]
  EXPOSE 8093*
  </code></pre>
  <p>Please suggest a solution.</p>