Fix glibc-patch/flake.nix build

[gcurtis]

The nix build for the glibc-patch flake fails in the following ways:

• The flake and its shell script need to be re-added to git. Nix only allows flakes to be built in a git repo if they’re staged and up-to-date.
• The flake reference is a relative path:

error: cannot fetch input 'path:./glibc-patch?lastModified=1&narHash=sha256-nbzIMxg2Ep3APeOoXex/3g0DswM1zs7ER1RQxJ62Vs8%3D' because it uses a relative path