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>

While scanning, sane unbinds usb device from usblp module. This
patch creates a saned wrapper that keep track of all usb devices
binded to usblp before saned is launched and rebind them back
if not still bound after saned exits.

This workaround is only effective if saned is launched by a super
daemon like xinetd as it needs to exit after scan job finish. If
not, printing will not be available while saned service is running.

Write access to /sys/bus/usb/drivers/usblp/bind is required. So,
normally it would require root access.

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