Support Apple Silicon and aarch64 Linux

This PR adds support for aarch64 hosts, most commonly Apple Silicon Macs. Updating the version of config.guess from the ancient copy bundled with the deps makes everything work. Surprisingly, it seems like all of the GNU tools built for aarch64 even back in 2006, despite the architecture not having… existed.

README.md

@@ -143,9 +143,3 @@ If the assignments repo has changed, either due to assignments being changed or
 This is due to windows placing return characters in the strings that get
 passed to the scripts. Please use git bash or a terminal that does UNIX
 string passing.
-
-**Cannot figure out the host**
-This occurs within newer level Macs that use Apple Silicon, docker
-currently requires x86 architectures to work, you'll need to use the
-student environment.
-