Disable ICache emulation for some games

Specifically, 'Scooby-Doo! Mystery Mayhem', 'Scooby-Doo! Unmasked', 'Ed, Edd n Eddy: The Mis-Edventures', and the Wii version of 'Happy Feet'.

The JIT cache causes problems with emulated icache invalidation in these games, resulting in areas failing to load.

Source/Core/Core/ConfigManager.h

@@ -111,6 +111,7 @@ struct SConfig
   bool bFastmem;
   bool bFPRF = false;
   bool bAccurateNaNs = false;
+  bool bDisableICache = false;
 
   int iTimingVariance = 40;  // in milli secounds
   bool bCPUThread = true;