stm32: Fix linker script on Ubuntu

This fixes a problem where certian segments are missing on Ubuntu.
chg: Automatically charge if battery is low

If the battery is less than 95%, and if the current consumption is low
(e.g. < 1 mA), then engage the charger and charge up the battery.

Note that this can be dangerous, because we hardcode the current that
can be sourced by our power supply.