tesseract-ocr: new package

tesseract-ocr: new package

Signed-off-by: Gilles Talis <gilles.talis@gmail.com>
[Thomas:
 - remove jpeg, tiff and libpng dependencies, they do not seem to be
   used
 - add host-pkgconf as a dependency, since the configure script uses
   PKG_CHECK_MODULES()
 - pass --disable-opencl to explicitly disable OpenCL support
 - add comment to explain why we don't add support for cairo, pango and
   icu as optional dependencies.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>