Figure out a portable way to extract `.tar.xz` archives

[alexrp]

See:

zig-toolsets/src/Directory.Build.targets

Lines 23 to 28 in c49c7d1

	<!--
	TODO: We currently assume that the tar program can extract XZ archives. This
	is not the case for the tar that ships with Windows. So, this target only
	really works on Unix systems or in environments that have a proper tar (e.g.
	Git Bash).
	-->