Add support for FreeBSD AArch64

[ararslan]

Accompanying Yggdrasil PR: JuliaPackaging/Yggdrasil#9220

I'll flip this out of draft mode once all compilers have been built.

[giordano]

With reference to JuliaPackaging/Yggdrasil#9220 (comment), for gcc I was thinking of

BinaryBuilderBase.jl/src/Rootfs.jl

Lines 578 to 584 in 56580d9

	function find_shard(name, version, archive_type; target = nothing)
	# aarch64-apple-darwin is a special platform because it has a single GCCBootstrap
	# with a version number different from any other platforms: match this shard with a
	# regular GCCBootstrap v11 for the host.
	if name == "GCCBootstrap" && version == v"12.0.1-iains" && target !== nothing && Sys.islinux(target)
	version = v"12.1.0"
	end

but that was specific to aarch64-darwin where we have a different toolchain version number under the hood (the user doesn't need to know it), but this may just work for aarch64-freebsd

BinaryBuilderBase.jl/src/Rootfs.jl

Lines 586 to 593 in 56580d9

	for cs in all_compiler_shards()
	if cs.name == name && cs.version == version &&
	(target === nothing || platforms_match(cs.target, target)) &&
	cs.archive_type == archive_type
	return cs
	end
	end
	return nothing

However, if we only have GCC >= 7, you probably need to adapt

BinaryBuilderBase.jl/src/Rootfs.jl

Lines 763 to 770 in 56580d9

	# If this is an platform that has limited GCC support (such as aarch64-apple-darwin),
	# the libgfortran versions we can expand to are similarly limited.
	local libgfortran_versions
	if Sys.isapple(platform) && arch(platform) == "aarch64"
	libgfortran_versions = [v"5"]
	else
	libgfortran_versions = [v"3", v"4", v"5"]
	end

gcc 7 has libgfortran v4, so you have to exclude v3

[giordano]

Reminder: you'll need to add aarch64-freebsd to the list of platforms incompatible with Julia v1.5 at https://github.com/JuliaPackaging/BinaryBuilder.jl/blob/8aadff4c54e12a31fe605defd81d99da78c60af2/src/AutoBuild.jl#L199

[ararslan]

Ah thank you! PR: JuliaPackaging/BinaryBuilder.jl#1342

[ararslan]

I also bumped the version so that we can tag a new release.