Interpreter: software-based flush-to-zero

bDAZ is now called bFlushToZero to better reflect what it's actually
used for.

I decided not to support any hardware-based flush-to-zero on systems
that don't support this for both inputs _and_ outputs. It makes the code
cleaner and the intersection of CPUs that support SSE2 but not DAZ
should be very small.

Source/Core/Common/Src/CPUDetect.h

@@ -45,7 +45,10 @@ struct CPUInfo
 	bool bAES;
 	// FXSAVE/FXRSTOR
 	bool bFXSR;
-	bool bDAZ;
+	// This flag indicates that the hardware supports some mode
+	// in which denormal inputs _and_ outputs are automatically set to (signed) zero.
+	// TODO: ARM
+	bool bFlushToZero;
 	bool bLAHFSAHF64;
 	bool bLongMode;