Add build settings for Linux with VIA C3 processor

I run a headless squeezeplay server on an old HTPC with Debian Linux on a VIA C3 processor. To build, I had to create an alternative Makefile for the VIA C3, which might be useful to others. Please include it!

Btw: running squeezeplay headless (without a monitor or X11 even installed) entails installing Xvfb + Xvfb-run, and starting squeezeplay like `'/usr/bin/xvfb-run /path/to/squeezeplay/bin/squeezeplay.sh'`