textproc/ibus: Update to 1.5.31

• Switch to DISTVERSION
• Switch to MASTER_SITES (release tarball)
• Add GTK4 option
• Enable by default GTK3, GTK4 and WAYLAND [1] options (disable GTK2)
• Remove reference to KDE4 in pkg-message
• Remove MAKE_JOBS_UNSAFE restriction

[1] Wayland is enabled by default in x11-toolkits/gtk{30,40}

ChangeLog: https://github.com/ibus/ibus/releases/tag/1.5.31
PR: 283516