68b5fdce2d
Commit e20232eab6 moved ZIG_GLOBAL_CACHE_DIR setup from an
addEnvHooks call into zigConfigurePhase. This broke all zig packages
that referenced $ZIG_GLOBAL_CACHE_DIR in postPatch or postUnpack,
since that variable is no longer set until configurePhase runs.
Move the symlink creation to postConfigure for all affected packages.