Fix potential memory leak on Linux
Fix potential memory leak on Linux

The function slurp_all_batteries(), on Linux, allocates memory
dynamically

Signed-off-by: Olivier Gayot <177cb43a9a0ccab7ae6d0e6a74e79a9be7a5415d@sigexec.com>

Gravemind/i3status,peder2tm/i3status-netdev,Gravemind/i3status,lexszero/i3status,i3/i3status,i3/i3status,Gravemind/i3status,Dettorer/i3status,i3/i3status,Dettorer/i3status,peder2tm/i3status-netdev,peder2tm/i3status-netdev,lexszero/i3status,peder2tm/i3status-netdev,Gravemind/i3status,i3/i3status,lexszero/i3status,lexszero/i3status,Dettorer/i3status,Dettorer/i3status