- updated to 1.0.21

- updated to 1.0.21
- added link patch, updated pl.po-update patch
- hp_rts88xx addon backend already obsoleted by upstream hp3500+rts8891
- added upstream i18n patch
- enable pthread (needed by mustek_usb2 backend)
- separated v4l backend (libv4l dependency)
- -devel R: libusb-devel, libieee1284-devel (but not libv4l-devel)

Changed files:
    sane-backends-1.0.21-i18n.patch -> 1.1
    sane-backends-hp_rts88xx-fixes.patch -> 1.5
    sane-backends-hp_rts88xx.patch -> 1.2
    sane-backends-link.patch -> 1.14
    sane-backends-pl.po-update.patch -> 1.5
    sane-backends.spec -> 1.132