Make OSX building and internal libraries work more nicely, update config.guess and config.sub

Hi Sekai devs! I've been doing a bit of Ponscripter development lately, and figured it'd be nice to contribute some OSX stuff to this fork instead of one sitting on my local machine and not heading much further.

First thing this PR does is add some more stuff to the gitignore. Just some stuff that gets autogenerated and we can safely ignore, not a big change.

I change the included folder from the extlib folder, to what it is now with the SDL2 change, as well as adding the smpeg2 include folder so we can actually use the built library effectively.

I also updated both config.guess and config.sub. Under OS X 10.9, the older versions were seeing my X86_64 processor as an i386, and stuffing compilation. OS X compilation still doesn't work perfectly, but I'm hoping I can contribute some more fixes along the line and somewhat patch it together!