This is now provided by default in saturn/common.mk.
Also updates moved header names, changed bit macro names, and changes
to the common.mk build process.
The Saturn BIOS does not (un)initialize the DSP. Without zeroizing the DSP
program, the SCSP DSP appears to have a program that continuously writes to
0x30000 through 0x3ffff in sound RAM, which has the effect of destroying any
samples stored there.
