naomi.cpp: rhytngk black screen on boot

[angelosa]

• On -nodrc it expects a flag to return a 0xff at PC=0xc06dec4 R8=$c50ebf4, coming from $5f7008 a.k.a. gdlen register in ROM board;
• On x86 -drc it keeps looping at this lovely SH4 snippet:

0C110760: 0780 ??????  $0780
0C110762: 0E11 ??????  $0E11
0C110764: 7301 ADD     #$01,R3
0C110766: 6183 MOV     R8,R1
0C110768: 3630 CMP/EQ  R3,R6
0C11076A: 2722 MOV.L   R2,@R7
0C11076C: 8FF8 BFS     $0C110760
0C11076E: 312C ADD     R2,R1

I doubt it's trying to trap on these illegal instructions, more likely a loading miss in the chain of operations.