Log Message:
poppler: update to 0.68.0.

Release 0.68.0
        core:
         * Add Reason and Location to SignatureInfo. Bug #107299
         * Fix memory misuse on signature handling
         * Fix security issues found by oss-fuzz
         * Don't give a warning when Marked value is false. Bug #107430

        qt5:
         * Add Reason and Location to SignatureInfo. Bug #107299

        cpp:
         * Add rotation() to text_box. Bug #106562
         * Fix build with MSVC

        utils:
         * pdftoppm: Add -jpegopt optimize option support
         * pdftocairo: Add -jpegopt optimize option support
         * pdftohtml: Add option to not round coordinates
         * pdftohtml: Fix possible crash. Bug #107316

        build system:
         * Use OpenJpeg cmake config file instead of pkgconfig
         * Remove wchar_t- on MSVC