Add package clBLAS

[MathiasMagnus]

Following up on previous work of clFFT, I would like to add another clMath library: clBLAS

Few notes about the port:

• I still don't know how to properly generate the patch files once I have both the original and the ported version on disk. I simply overwrite the original ones, even though I know it's frowned upon due to increasing the repo size. If someone documented how to do it, I could do it for this and future ports as well.
• For some reason the debug CRT libraries are deployed beside the debug libraries. I don't quite know what is the reason behind this, so I just delete them, but this might not be the best approach.
• Instead of the approach with clFFT, I took a different and cleaner approach with the outdated FindOpenCL.cmake. I simply delete the outdated original from the source tree, use the built-in CMake version and rename the results to what the scripts expect. This was necessary because the scripts are MUCH longer and much more intricate.

Otherwise the library builds and is usable by 3rd party applications with the usual syntax provided by the deployed clBLASConfig.cmake.

[ras0219-msft]

Thanks for the PR!

I reverted the change to clfft because it causes failures if done in isolation. You may have local patches to buildtrees\clfft\ that cause it to work, so you'll need to revert those (simply delete buildtrees\clfft\ and it'll be recreated from scratch :)).

I wouldn't be opposed to adding the "cleaner" approach to clfft, but it'll need source patches to go in at the same time.

Finally, here[1] is an full example of how I create patch files. Essentially, just create a temporary git repo inside the buildtrees\clfft\src\clfft-x.y.z\ folder and use git diff to make the patch file :)

[1] https://github.com/Microsoft/vcpkg/blob/a506559ba9ff9aab7a6176b43313a8ce26891269/docs/examples/patching-libpng.md