o add snes fatfs dummy

o add fatfs custom chip to bsnes
o finishes fatfs linux backend smaple

snes/fatfstest/debug.h

@@ -0,0 +1,6 @@
+void initDebugMap(void);
+void debug(void);
+void int2hex(unsigned long i, char *buf,word size);
+void printDebugScreen(char* line,word y);
+void enableDebugScreen(void);
+void printf(char* line);