- 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
