Look for Threads dependency in CMake config script #42

	# Based on GTSAM file (by @ProfFan)
	name: CI Linux

	on: [push, pull_request]

	jobs:
	build:
	name: ${{ matrix.name }} ${{ matrix.build_type }}
	runs-on: ${{ matrix.os }}

	env:
	CTEST_OUTPUT_ON_FAILURE: ON
	CTEST_PARALLEL_LEVEL: 1
	CMAKE_BUILD_TYPE: ${{ matrix.build_type }}
	VERBOSE: 1 # to show all cmake scripts debug info

	strategy:
	fail-fast: false
	matrix:
	# Github Actions requires a single row to be added to the build matrix.
	# See https://help.github.com/en/articles/workflow-syntax-for-github-actions.
	name: [
	ubuntu-20.04-gcc,
	ubuntu-20.04-clang,
	ubuntu-22.04-gcc,
	ubuntu-22.04-clang,
	]

	build_type: [ Release ]
	include:
	- name: ubuntu-20.04-clang
	os: ubuntu-20.04
	compiler: clang

	- name: ubuntu-20.04-gcc
	os: ubuntu-20.04
	compiler: gcc

	- name: ubuntu-22.04-gcc
	os: ubuntu-22.04
	compiler: gcc

	- name: ubuntu-22.04-clang
	os: ubuntu-22.04
	compiler: clang

	steps:
	- name: Checkout
	uses: actions/checkout@master

	- name: Git submodule
	run: \|
	git submodule sync
	git submodule update --init --recursive

	- name: Install Dependencies
	run: \|
	sudo apt-get -y update
	sudo apt-get -y upgrade

	sudo apt install -y \
	cmake build-essential cmake

	if [ "${{ matrix.compiler }}" = "gcc" ]; then
	sudo apt-get install -y g++ g++
	echo "CC=gcc" >> $GITHUB_ENV
	echo "CXX=g++" >> $GITHUB_ENV
	else
	sudo apt-get install -y clang g++-multilib
	echo "CC=clang" >> $GITHUB_ENV
	echo "CXX=clang++" >> $GITHUB_ENV
	fi

	- name: CMake configure
	run: \|
	cmake -DCMAKE_VERBOSE_MAKEFILE=ON \
	-H. -Bbuild

	- name: Build
	run: \|
	make -C build

	- name: Run tests
	run: \|
	ctest --verbose --test-dir build

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