lib/util/fault.c: Unify printing of the stack trace with the INTERNAL ERROR string

lib/util/fault.c: Unify printing of the stack trace with the INTERNAL ERROR string

We can diverged into the s3 and lib/fault panic action stuff once
we have printed the backtrace.

Our tests require we use the word PANIC, and some administrative scripts
might look for similar things, so keep those words.

The use of DEBUG(0, ... is deliberate to keep the output
of the PANIC line as consistent as possible with the historical smbd output.

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Thu Feb 27 05:09:44 UTC 2020 on sn-devel-184