FTBFS fixes, perl/python/libtool
    
    - drop RPATH according [1]
    - fix perl build issue
    - add BR tex(tabu.sty)
    - don't hack the build system peculiarities, and rather build
      without --with-python/--with-perl
    - use standard %py*{build,install} macros
    - rename gdal-python3 to python3-gdal
    
    Resolves: rhbz#1577185, rhbz#1606875
    
    [1] https://fedoraproject.org/wiki/RPath_Packaging_Draft