Hide X cursor on kiosk (touchscreen)

Pass -nocursor to startx so the mouse pointer never appears on the\nOnefinity touchscreen. Patched in all three boot paths: rc.local.fast\n(active), legacy rc.local, and the setup_rpi.sh bootstrap.

scripts/rc.local.fast

@@ -34,7 +34,9 @@ plymouth quit 2>/dev/null || true
 # late-boot units (bbctrl logrotate, etc.) don't block on it. Output
 # is redirected so the journal doesn't fill up with X warnings.
 cd /home/pi
-nohup sudo -u pi startx >/var/log/onefin-x.log 2>&1 &
+# `-- -nocursor` hides the X pointer; this is a touchscreen kiosk and
+# the mouse cursor only gets in the way.
+nohup sudo -u pi startx -- -nocursor >/var/log/onefin-x.log 2>&1 &
 disown
 
 exit 0