Switch to GitHub Actions for CI #4

	name: Presubmit

	permissions:
	contents: read

	on: [push, pull_request]

	jobs:
	build:
	name: Build all specs
	runs-on: ubuntu-latest

	steps:
	- uses: actions/checkout@v4
	with:
	fetch-depth: 0
	submodules: recursive

	- name: Install required packages
	run: \|
	sudo apt-get install -y libpango1.0-dev libwebp-dev ghostscript fonts-lyx jing
	sudo gem install asciidoctor -v 2.0.16
	sudo gem install coderay -v 1.1.1
	sudo gem install rouge -v 3.19.0
	sudo gem install ttfunk -v 1.7.0
	sudo gem install hexapdf -v 0.27.0
	sudo gem install asciidoctor-pdf -v 2.3.4
	sudo gem install asciidoctor-mathematical -v 0.3.5

	- name: List git tag
	run: \|
	git describe --tags --dirty

	- name: Generate core specs
	run: \|
	make -O -j5 api c env ext cxx4opencl

	- name: Generate extension specs
	run: \|
	make extensionshtml

	- name: Generate reference pages
	run: \|
	make -O -j manhtmlpages

	- name: Validate XML
	run: \|
	make -C xml validate

Provide feedback