devel/libhtp: Update to 0.5.24

This update fixes a HTTP connect handling issue [1]

https://github.com/OISF/libhtp/blob/0.5.24/ChangeLog

[1] https://github.com/OISF/libhtp/pull/150

PR: 220025
Submitted by: Franco Fichtner <franco opnsense org>
MFH: 2017Q2