hooks/pre-auto-gc: look in sysfs to see if a battery is known.

Barring any kernel bugs, if this directory exists and there is
a symlink in there (which will point to the battery object),
that means there is a battery known to the kernel.

No symlink should mean no battery as far as the kernel is concerned.

Change-Id: Ib12819a5bbb816f0ae5ca080e5812a2db08441e9
1 file changed