Suport bloomberg p2996 clang (or try to!) cc @katzdm #93

	name: Build
	on:
	push:
	workflow_dispatch:
	jobs:
	build:
	runs-on: ubuntu-latest
	strategy:
	matrix:
	include:
	- image: 20.04
	suffix:
	- image: 18.04
	suffix: -18.04
	# Some older clangs (<10) needs to be an older glibc, as comes with 18.04 in order to build 9.* and earlier.
	# otherwise we somehow need to apply 947f9692440836dcb8d88b74b69dd379d85974ce to get the sanitizer
	# to build.
	steps:
	- name: Docker Setup Buildx
	uses: docker/setup-buildx-action@v2
	- name: Docker Login
	uses: docker/login-action@v2
	with:
	username: ${{ secrets.DOCKERHUB_USERNAME }}
	password: ${{ secrets.DOCKERHUB_PASSWORD }}
	- name: Build and push to Docker Hub
	id: hub_build
	uses: docker/build-push-action@v4
	with:
	push: ${{ github.ref == 'refs/heads/main' && 'true' \|\| 'false' }}
	tags: compilerexplorer/clang${{ matrix.suffix }}-builder:latest
	cache-from: type=registry,ref=compilerexplorer/clang${{ matrix.suffix }}-builder:latest
	cache-to: type=inline,mode=max
	file: Dockerfile
	build-args: image=${{ matrix.image }}
	- name: Docker Hub Image Digest
	run: echo ${{ steps.hub_build.outputs.digest }}

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