Use SZFMT for printing size_t
Initialize a couple variables mingw complains about
Update cross-compiler toolchain to work better with Qt
Fix 5.1 surround sound

Apparently, 5.1 surround sound is supposed to use the "side" channels, not the
back channels, and we've been wrong this whole time. That means the "5.1 Side"
is actually the correct 5.1 setup, and using the back channels is anomalous.

Additionally, this means the 5.1 buffer format should also use the the side
channels instead of the back channels.

A final note: the 5.1 mixing coefficients are changed so both use the original
5.1 surround sound set (with the surround channels at +/-110 degrees). So the
only difference now between 5.1 "side" and 5.1 "back" is the channel labels.
Use shorter display names for the surround sound config options
Use a separate macro for the max output channel count