Change build procedure to not require renaming directories of Visual Studio Install

[rajha-korithrien]

This is not an issue so much as a suggestion.
I struggled with getting the cmake windows build working, because I kept hitting the compiler heap error C1060.
I found the fix to be:

• ensure you ran vcvarsall.bat with the x64 argument:

"C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Auxiliary\Build\vcvarsall.bat" x64

• pass the -T flag to cmake.

cmake .. -A x64 -T host=x64 .....

For a run of cmake in an empty directory (doing an out of source build). This caused everything to be built using the x64 64-bit tool chain instead the x86 32-bit tool chain. I was then able to get a complete and clean build on windows. No need to rename directories.
I file this issue so you can have an easier time and change your instructions in README.md because your github comes up when googling building tensorflow on windows, so it will make things easier for other folks as well.

[faisalthaheem]

Hi Rajha

Could you please create a pull request, it would be nice to have you contribute.