Replace this repo with chfast/ethash

[chfast]

Replace this repo with https://github.com/chfast/ethash.
This one can be renamed to ethash-legacy and should be archived.

Identify current users of this library.

• Python / pyethash ?
• ethereum-js ?

[manwapri]

ethash clone and compile procedure:

sudo yum install -y *gcc*
sudo yum install -y *g++*
sudo yum install -y *libboost*
sudo yum install -y python
sudo yum install -y python-virtualenv*
sudo yum install -y cryptopp
sudo yum install -y *opencl*
wget https://raw.githubusercontent.com/Xilinx/XRT/master/src/runtime_src/tools/scripts/xrtdeps.sh
sudo sh xrtdeps.sh
sudo yum install -y cmake
sudo yum install -y git
git clone https://github.com/ethereum/ethash.git
cd ethash/
git checkout v23.1
sed -i '16 s/^/pip install --upgrade pip\npip install nose\npip install pysha3\n/' ./test/python/test.sh
sed -i '39 s/^/#include \n/' ./src/benchmark/benchmark.cpp
make
cd test/c/build
make ethash
make Benchmark_FULL
./src/benchmark/Benchmark_FULL