NAT: Fix #else /* VBOX */ comments to reflect the condition when that #else is selected. While here, add spaces inside cramped #endif /*VBOX*/ comments. Same object code is generated.

NAT: prevent NAT thread from infinite loop on PowerOff if DNS server(s) not accessible.

NAT: Use RW critsect to protect the handler chain list against concurrent access

NAT: warnings [-Wunused-macros]

Devices: whitespace cleanup

NAT: globals

NAT: export of libalias