Added Intel MKL graph optimization code and the ability to enable MKL when...

Added Intel MKL graph optimization code and the ability to enable MKL when running configure. (#6921)

* Added Intel MKL graph optimization code and the ability to enable MKL when running configure.

* Fixed inclusion of MKL into build files.

* Made changes to MKL graph optimization files based on review comments.

* Adding support for MKL matmul op

* Revert "Adding support for MKL matmul op"

This reverts commit 20d6cdd865dbe790bd03765e82b709bd750d8823.

* Changes based on Vijay Vasudevan's comments

* Made format-related fixes to some build files.

* Setting the execute bit (755) for tensorflow/tools/pip_package/build_pip_package.sh