Netboot fixes:

Netboot fixes:
- the ARRAY_SIZE macro is no more needed here,
- use of cfgpath to have the actual config path to apply for mac *and* ip
lookup,
- no need to free a buffer big enough, and besides malloc(9) was not
enough ("/etc/" missed),
- use of intermediate length variables to avoid unneeded calls to strlen()
and strrchr().
benoit.guillon <benoit.guillon@tele2.fr>