Add USE_LAPACK as CMake option, with default true #178

	---
	name: CMake MKL

	on: [push, pull_request]

	jobs:
	linux:
	runs-on: ubuntu-latest
	steps:
	- name: Intel Apt repository
	run: \|
	wget https://apt.repos.intel.com/intel-gpg-keys/GPG-PUB-KEY-INTEL-SW-PRODUCTS-2023.PUB
	sudo apt-key add GPG-PUB-KEY-INTEL-SW-PRODUCTS-2023.PUB
	rm GPG-PUB-KEY-INTEL-SW-PRODUCTS-2023.PUB
	echo "deb https://apt.repos.intel.com/oneapi all main" \| sudo tee /etc/apt/sources.list.d/oneAPI.list
	sudo apt-get update

	- name: Install Intel oneAPI
	run: sudo apt-get install intel-mkl

	- name: Setup Intel oneAPI environment
	run: \|
	# TODO: hack to set MKLROOT for now
	echo "MKLROOT=/usr/lib/x86_64-linux-gnu" >> $GITHUB_ENV
	# source /opt/intel/mkl/bin/mklvars.sh

	- name: checkout project code
	uses: actions/checkout@v3

	- name: Build SCS MKL and test
	run: \|
	mkdir out
	export INSTALL_DIR=$PWD/out
	export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$INSTALL_DIR/lib
	mkdir build
	cd build
	cmake -DBUILD_TESTING=ON -DCMAKE_INSTALL_PREFIX:PATH=$INSTALL_DIR ..
	make
	make install
	ctest --output-on-failure
	cd ../docs/src/examples/
	gcc -I$INSTALL_DIR/include/scs -L$INSTALL_DIR/lib/ qp.c -o qp.out -lscsmkl
	./qp.out

Provide feedback