emulators/higan: Return to pool
While I'm here:
- remove AUDO_DRIVER, INPUT_DRIVER and VIDEO_DRIVER variables, they was used to patch target-tomoko/GNUMakefile. This directory doesn't exist and the relevant REINPLACE_CMD removed at commit 597ca5a01e3893880470afdd10a9cc4a0cdaa93a.
- remove unused options: OSS, INPUT_X. The OSS doesn't exist and INPUT_X sets only INPUT_DRIVER variable (see above).
- pet portlint, portfmt, portclippy
PR: 286810