games/instead: enable harfbuzz support, fix lua(jit) deps

• Enable harfbuzz support which is now available in SDL2_ttf (disabled by default according to upstream setting) [1]
• Switch luajit dependency to USES=luajit (it also should now work on powerpc, so a related hack is no longer needed)
• Fix dependency on lua
• Remove no longer needed CMake argument

PR: 271545 [1]
Reported by: jbeich [1]