Various fixes + cleanup.

- Add parts.rst documentation for Linux kernel.
- Completely fix problems caused by new bootstrap, update checksums for
  /usr.
- Globalise populate_device_nodes.
- Enable deblobbing.

sysc/run.sh

@@ -8,6 +8,7 @@
 
 set -e
 
+# shellcheck source=sysglobal/helpers.sh
 . helpers.sh
 
 export PATH=/usr/bin:/usr/sbin
@@ -26,6 +27,8 @@ create_fhs() {
     mount -t tmpfs tmpfs /tmp
 }
 
+populate_device_nodes ""
+
 create_fhs
 
 build bash-5.1