linux: omit build id (#106648)

Don't include an ​NT_GNU_BUILD_ID (that is randomly generated
at build time).

This improves the kernel reproducibility: when also disabling
the MOUDLE_SIG and SECURITY_LOCKDOWN_LSM options the build
is bit-by-bit reproducible.

pkgs/os-specific/linux/kernel/manual-config.nix

@@ -113,6 +113,13 @@ let
             sed -i "$mf" -e 's|/usr/bin/||g ; s|/bin/||g ; s|/sbin/||g'
         done
         sed -i Makefile -e 's|= depmod|= ${buildPackages.kmod}/bin/depmod|'
+
+        # Don't include a (random) NT_GNU_BUILD_ID, to make the build more deterministic.
+        # This way kernels can be bit-by-bit reproducible depending on settings
+        # (e.g. MODULE_SIG and SECURITY_LOCKDOWN_LSM need to be disabled).
+        # See also https://kernelnewbies.org/BuildId
+        sed -i Makefile -e 's|--build-id|--build-id=none|'
+
         sed -i scripts/ld-version.sh -e "s|/usr/bin/awk|${buildPackages.gawk}/bin/awk|"
       '';