use the app-office/openoffice{,-bin} implementation for extensions

Other “office_implementation” USE_EXPAND flag values

Use Flag Description
office_implementation_libreoffice use the app-office/libreoffice{,-bin} implementation for extensions
office_implementation_openoffice use the app-office/openoffice{,-bin} implementation for extensions

All packages providing a “office_implementation_openoffice” USE flag (8)