Replace deprecated IO::Socket::INET6 with IO::Socket::IP.

Do not mix Perl read() with sysread(). Data could get stuck in the
buffered IO and test run-regress-args-get-1073741824.pl would fail
on slow hardware. Introduce a common function read_part() that

Do not mix Perl read() with sysread(). Data could get stuck in the
buffered IO and test run-regress-args-get-1073741824.pl would fail
on slow hardware. Introduce a common function read_part() that
uses Perl read(). Limit debug output to one line per 1% of data.
Remove unused function http_server(). Fix whitespace. Cleanup
Makefile.

show more ...

Add httpd regression tests based on bluhm's regression suite for
relayd - "bluhm test". This is just the initial version, more tests
and changes will be done.

As discussed with bluhm@ florian@