Complement cmake script to compile tensorflow with mkl and mkldnn on Windows (#16936)

Complement cmake script to compile tensorflow with mkl and mkldnn on Windows (#16936)

* Add build batch for windows

* Automaticaly find python, cuda, mkl runtimes in PATH

* auto select cmake generator

* Add external library mkldnn. Add options for mkl and mkldnn

* fix syntax error in make.bat

* Fix errorlevel syntex bug in make.bat

* Add /arch:avx2 flags to enable avx2 on windows

* Revert to keep `tensprflow_WIN_CPU_SIMD_OPTIONS` unchanged, add an option `tensorflow_ENABLE_MKL_SUPPORT` to include MKL compilation. Still specify SIMD flags by setting `tensorflow_WIN_CPU_SIMD_OPTIONS` to such as '/arch:AVX2'

* Fix a mistake of CUDA path in make.bat

* resolve conflict in mkl_cpu_allocator.h

* Improve error detection

* Use where /Q to detect cmd environment

* fix "ELSE IF" the syntax error in make.bat

* update README.md, wrap windows based codes by #ifdef _WIN32

* unistd.h is not needed in mkl_cpu_allocator.h any more in master branch

* Remove inline of kMaxLimitStr, which causes compile error in VS2015

* Add static_cast in  to fix compile error

* remove make.bat

* Removed make.bat description part