lwip: Merge upstream commit "Add some comments to places where we cast through a void* to get rid of alignment warnings"
lwip: Merge upstream commit "Add some comments to places where we cast through a void* to get rid of alignment warnings"

Upstream commit: 087ecab8913dc3e17a4ba22633ef7b78a80b8a56

ambrop72/aprinter,ambrop72/aprinter,ambrop72/aprinter,johnkingsley/aprinter,ambrop72/aprinter,johnkingsley/aprinter,ambrop72/aprinter,johnkingsley/aprinter,johnkingsley/aprinter,johnkingsley/aprinter,johnkingsley/aprinter,ambrop72/aprinter,ambrop72/aprinter,johnkingsley/aprinter