r7525: Unify lp_load(), load_interfaces and logging setup into popt().

r7525: Unify lp_load(), load_interfaces and logging setup into popt().

There is now a new --debug-stderr option to enable debug to STDERR.

popt isn't perfect, but the callbacks are used in all the main Samba
binaries, and should be used in the rest.  This avoids duplicated
code, and ensures every binary is setup correctly.

This also ensures the setup happens early enough to have -s function,
and have a correct impact on the credentials code.  (Fixing a bug that
frustrated tridge earlier today).

The only 'subtle' aspect of all this is that I'm pretty sure that the
SAMBA_COMMON popt code must be above the CREDENTIALS code, in the
popt tables.

Andrew Bartlett
(This used to be commit 50f3c2b3a22971f40e0d3a88127b5120bfc47591)