Just Need runtime tests

* libsane dependency on libusb moved to those drivers that requires it
* clean up some ./configure args
* added saned-ricoh2 for new backend
* enabled saned-gphoto2 (after c8fbe26c53)
* disabled kvs40xx and mustek_usb2 that requires pthread while the issue is
not solved (https://gitlab.com/sane-project/backends/issues/153)
* patches refreshed:
 - 002-remove-uneeded.patch
* patches dropped:
 - 031-fix_uclibc.patch
 - 050-remove_linked_libs_for_unused_preload.patch (with --disable-preload)

Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>