Update doxygen to version 1.9.6 / rev 92 via SR 1082738
    
    https://build.opensuse.org/request/show/1082738
    by user dimstar_suse
    - Re-download patches: the server presents them with shorter hash
      refs:
      * Fix-boundingbox-parsing_part1.patch
      * Fix-boundingbox-parsing_part2.patch
      * Fix-boundingbox-parsing_part3.patch
      * Fix-boundingbox-parsing_part4.patch
    
    - Add _multibuild to define 2nd spec file as additional flavor.
      Eliminates the need for source package links in OBS.