libhtp: Update to 0.5.40 - needed for 'suricata'

libhtp: Update to 0.5.40 - needed for 'suricata'

For details see:
https://github.com/OISF/libhtp/releases/tag/0.5.40

    "uri: optionally allows spaces in uri
    ints: integer handling improvements
    headers: continue on nul byte
    headers: consistent trailing space handling
    list: fix integer overflow
    util: remove unused htp_utf8_decode
    fix 100-continue with CL 0
    lzma: don't do unnecessary realloc"

Signed-off-by: Matthias Fischer <matthias.fischer@ipfire.org>
Reviewed-by: Adolf Belka <adolf.belka@ipfire.org>