comms/xastir: Update to 2.1.8

ChangeLog: https://github.com/Xastir/Xastir/releases/tag/Release-2.1.8

While here:

• Remove gettext and python from USES. The port doesn't used them anymore.
• Remove comment
• Move patch to .am file instead of generated .in file
• Remove sparc64 patch (architecture is UNSUPPORTED in 13 and above)
• Add USES=autoreconf

This last item allows us to bypass bootstrap.sh. The language preprocessing is
already done in the config directory so there is no need to do it as a bootstrap
step.

PR: 259669
Reported by: russo@bogodyn.org (xastir developer)
Approved by: carl@stagecraft.cx (maintainer, timeout > 1 month)