This reverts commit c17b8a599e.

The commit made compile error and its intention is unclear.

Adding the makefile options ADB_MOUSE_ENABLE and ADB_MOUSE_ACCMAX.
Might have gone overboard with comments, and tried but failed at not
adding more than necessary outside the converter/adb_usb/ folder.

Keypresses would be forgotten if they began while ghosting, even if they
were still pressed after ghosting ended.