x11-toolkits/libXt: Update to 1.3.1

Update Comment, WWW and pkg-descr.
Remove REINPLACE_CMD added in PR 166373 to support clang cpp.

https://lists.x.org/archives/xorg-announce/2024-November/003560.html

PR: 286918
Approved by: x11 (arrowd)
Reviewed by: osa (mentor), fluffy (mentor)