Changes to the IBM 386/486 and RapidCAD CPUs

- Disabled the 'is486' flag and moved them to 386 timings
- Disabled cache on startup, enable-able later
- RapidCAD fixes (permanently disable L1, correct EDX reset)

src/cpu_common/x86_ops_misc.h

@@ -741,22 +741,12 @@ static int opCLTS(uint32_t fetchdat)
 
 static int opINVD(uint32_t fetchdat)
 {
-        if (!is486) 
-        {
-                x86illegal();
-                return 1;
-        }
         CLOCK_CYCLES(1000);
         CPU_BLOCK_END();
         return 0;
 }
 static int opWBINVD(uint32_t fetchdat)
 {
-        if (!is486) 
-        {
-                x86illegal();
-                return 1;
-        }
         CLOCK_CYCLES(10000);
         CPU_BLOCK_END();
         return 0;