The pam_systemd_home PAM_TEXT_INFO patch (systemd/systemd#40412) has been
merged upstream and is now available in the locked nixpkgs revision.

This overlay was causing a massive rebuild cascade: since systemd is a
transitive dependency of virtually every package (via dbus, polkit, udev,
glib, gtk, qt, etc.), patching it forced from-source rebuilds of packages
like inkscape, openjdk, qtbase6, and hundreds of others that would
otherwise be fetched from the binary cache.

Signed-off-by: vadik likholetov <vadikas@gmail.com>

The existing cross-compilation overlay fixed EFI_ARCH detection and
AR/RANLIB but missed three issues causing build failures:

sbsigntool:
- CCAN configurator compiled for target arch could not execute on build
  host. Fix: override CC to native compiler for create-ccan-tree.
- ./configure lacked --host/--build flags for cross-compilation.
- help2man cannot run cross-compiled binaries. Fix: exclude docs.

efitools:
- Default `all` target runs freshly-built tools (cert-to-efi-sig-list,
  sign-efi-sig-list) for cert generation, which fails when cross-compiled.
  Fix: build only CLI binaries, skip cert/auth generation.

Signed-off-by: vadik likholetov <vadikas@gmail.com>