Twelve login terminals, root only, console fixes, a faster build, a Niveus splash, and X back on evdev

- tty1-tty12 all run login; the image has only root. /dev/tty7..12 could not
  be written (cdev.c knew minors 10-16 only), which sent their jobs into a
  restart storm that took the supervisor down; fixed, and stat reports them as
  Linux's tty7..12.
- Erasing text at a prompt did nothing: erase_one sent a bare backspace, which
  only moves; it and the echo path now send back-blank-back through vt_feed.
- A white cursor block was left at the end of every line of a verbose boot:
  a line feed at the bottom scrolls the pixels, cursor included, and the
  cursor was erased after the scroll. It comes off first now. A blank cell is
  also marked dirty, which it was not.
- ldlsd died with a general protection fault on real hardware in its variadic
  log function: Linux module code calls with an 8-byte-aligned stack and an
  unset %al, and the prologue's movaps faults. LDLS guest code is built with
  -mstackrealign.
- make iso took over a minute for any change, because staging r8169 rewrote
  the same files and every mtime moved; it now replaces files only if their
  contents differ (about 10 s).
- The loader's splash is redrawn in the boot manager's style, and the boot
  manager shows its cursor whenever a pointer device exists.
- xf86-input-libinput is out of the image again: with it Xorg took both
  keyboard and pointer from libinput and, on the user's laptop, neither worked.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EVRhxi9zpdW2uDUN4FVcao

etc/schinit/tty3-shell.job

@@ -1,13 +1,6 @@
-# An interactive shell on /dev/tty3.
-#
-# NVT is 6 (include/dev/vt.h) and the kernel creates all six terminals, but only
-# two ever had anything running on them -- so Alt+F3 switched to a terminal
-# that was working perfectly and had nobody to talk to, which looks exactly
-# like a broken one.
-#
-# Identical to tty2-shell apart from the number. Six manifests rather than one
-# with a range, because schinit has no notion of a template and inventing one
-# for six lines each is the wrong trade.
+# A login on /dev/tty3: every one of the twelve virtual terminals asks who is there.
+# Alt+F3 (or Ctrl+Alt+F3) shows it. Twelve manifests rather than one with a
+# range, because schinit has no notion of a template.
 
 Label         = os.schos.tty3-shell
 Program       = /bin/sh