Fix #84: Remove code/unix-glibc2.lisp

This isn't referenced in worldcom or worldbuild anymore so we can
safely remove this.  Most of the required functionality was moved to
code/unix.lisp some time ago, so this isn't needed anymore.

Whatever functionality that is still left is in
contrib/unix/unix-glibc2.lisp, which we aren't removing.
2 jobs for rtoy-issue-84-remove-unix-glibc2 in 9 minutes and 28 seconds (queued for 2 seconds)
latest
Status Job ID Name Coverage
  Test
passed #4189
linux
linux-runner

00:04:18

passed #4190
osx
osx-runner

00:09:28