sdl_net: Fix multiple issues
sdl_net: Fix multiple issues

* Fix SECONDARY_ARCHITECTURES
* Enable x86_64
* Add checksums

koletzky/haikuports,koletzky/haikuports,miqlas/haikuports,haikuports/haikuports,haikuports/haikuports,haikuports/haikuports,moochris/haikuports,Begasus/haikuports,Begasus/haikuports,moochris/haikuports,Begasus/haikuports,Begasus/haikuports,miqlas/haikuports,nielx/haikuports,koletzky/haikuports,nielx/haikuports,haikuports/haikuports,miqlas/haikuports,Begasus/haikuports,moochris/haikuports,nielx/haikuports,haikuports/haikuports