Log Message:
sane-backends: update to 1.0.27.

New with 1.0.27 (see Note 1), released 2017-05-22:

* Significant enhancements to canon_dr, epjitsu, epsonds, fujitsu,
  genesys, hp3500, pixma and xerox-mfp backends.
* Minor updates, bugfixes or scanners added in several backends.
* 30+ new scanner models supported.
* Made libusb-1.0 the default for USB support (see Note 2).
* Switched code from C90 to C99 (Thanks to Volker Diels-Grabsch).
* Updated Linux USB3 workaround (see Note 3).
* Documentation and translation updates.
* Bugfixes (Avahi, threading, USB, ICC/PNG/JPEG, etc).
* Reduced compiler warnings, improved code (see Note 4).

Note 1: There is no 1.0.26 release of sane-backends. That number was
skipped so that our development version numbers would more clearly be
an extension of the prior release. This should make packaging a little
easier for our downstream users.

Note 2: On all systems, the --enable-libusb* flags are now ignored.
Instead, the --with-usb and --without-usb flags now control support.
When neither is given, USB support will be enabled if possible and
disabled otherwise.  If --with-usb is requested but not possible,
./configure will fail.  There is no support to prefer libusb-0.1 over
libusb-1.0.  When libusb-1.0 is not found, libusb-0.1 will be tried.

Note 3: The Linux USB3 workaround which was added in version 1.0.25 is
now disabled by default. If you have difficulty using a scanner which
previously worked, or intermittent scanner availability, try setting
the new environment variable SANE_USB_WORKAROUND=1 before starting
your frontend.

Note 4: A special thanks goes to Olaf Meeuwissen for picking up the
janitorial duties in sane-backends. He has found and fixed a large
number of long-standing bugs, curated our bug tracker, improved our
build scripts and docs, and provided user support. Thank you Olaf!