Initialize some local variables earlier

[mhorne]

Summary

Move the initialization of these variables to the beginning of their
respective functions.

On our end this creates a small amount of unneeded churn, as these
variables are properly initialized before their first use in all cases.
However, changing this benefits at least one downstream consumer
(NetApp) by allowing local and future modifications to these functions
to be made without worrying about where the initialization occurs.

[melifaro]

sys/netinet/ip_output.c

412

I'd prefer to retain this line, to ensure ia is still NULL after re-iterating in again:

[mhorne]

Address melifaro's comment.

[mhorne]

sys/netinet/ip_output.c

412

Thanks, good catch.

[emaste]

The GCC-tagged ones are probably workarounds for GCC 4.2.1 false positives and the initialization likely could just be removed.