Requirement of Software Renderering on Linux

[Ragora]

As per commit 309ee0d, I added a fallback to software rasterization in the SDL initialization. This is because on my machine here, I couldn't initialize with the hardware rasterizer for one reason or another and it was a general fix in the meantime until the reason why could be investigated.

This is more or less a note so that I don't forget or for someone else to look into the issue if I don't get to it in the meantime.

The affected machine is:
OS: Linux Mint 17.3 AMD64 (using KDE4)
Compiler: GCC 4.8.4
GPU: Radeon R7 360 w/ fglrx

If your machine is afflicted, you'll see this in your stdout output when running the game:

Renderer: Failed to initialize with hardware accelerated renderer, trying software.

That machine actually no longer quite exists, it is now running an NVidia GTX 750Ti with blackbox NVidia drivers in place of the Radeon, I need to try running the project on that when I can to see what the results are.

Edit The initialization issue also exists with the NVidia drivers here. At the least, the project shouldn't be terribly CPU heavy given that the only rasterization its actually doing is GUI and rendering the output from the OpenCL rasterizer as a texture underneath but it would be nice to work out why it might not be using hardware acceleration on a machine that clearly can provide it.

It also fails to actually spool up the OpenCL renderer, but that's another issue totally unrelated, likely mostly due to my switch from AMD to NVidia and still using the AMD OpenCL libraries.

[Ragora]

Apparently this is potentially the root of the cause: https://wiki.libsdl.org/FAQDevelopment#I_have_an_accelerated_video_card.2C_but_SDL_tells_me_that_I_have_zero_video_memory_and_no_acceleration.21

So pretty much deal with it on Linux, it's not a huge deal either way given that the 2D operations should be fairly easily dealt with even on not so good processors.

[Ragora]

@afritz1 Might want to just keep this on record somewhere in case someone asks later.