samples: net: dumb_http_server_mt: Add support for large file

If user sets CONFIG_NET_SAMPLE_SERVE_LARGE_FILE then the sample
will return 100KB file. By default 2KB file is returned.
This is used by the Docker based testing.

Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>
4 files changed