ghostscript: update GsDjVu version & fix warnings
--with-djvu was using slightly old code and producing warnings
builds clean now on osx 10.9
djvulibre: switch to git to fix corrupt output files on Mavericks
corruption fix: https://sourceforge.net/p/djvu/djvulibre-git/ci/2c904e0cb8314c0d2314331e5ac1eaf65a7757b4/
warnings fix: https://sourceforge.net/p/djvu/djvulibre-git/ci/308a3a10d5a027882c3ba80fd2d9087d2a63d099/

fixes #22076