add missing include file

Older systems does not seem to have PRIu32 without explicit declaration
of inttypes.h header.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
remove unnecessary braces

Code without unnecessary clutter is easier to read.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
clean up script running, and corresponding messaging

The earlier version was unnecessarily hard to read, and partly wrong.
For example the socket() call changed errno, that was part of later
evaluation what went wrong.  Occasionally that gave misleading messages
for instance if IPv6 was not enabled, and a script failed.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
fix make --quiet option to run scripts

The --quiet enabled --no-script by accident.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
clean some memory allocations up before exit

The socket answering thread is leaft allocated, as well as socket it
answers.  Oh well, kernel should know how to remove them from memory.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
add gnulib modules for greater portability

The list could still be incomplete, but at least it has few items more.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>