port: allow using N64 control schemes

change from Ext to another control scheme to activate

note that this will require rebinding keys, as the default config is for the Ext scheme

src/include/constants.h

@@ -694,6 +694,7 @@
 #define CONTROLMODE_22 5
 #define CONTROLMODE_23 6
 #define CONTROLMODE_24 7
+#define CONTROLMODE_PC 8 // "pc port" controls; enabled in the .ini file
 
 #define COUNTDOWNTIMERREASON_AI        0x01
 #define COUNTDOWNTIMERREASON_NOCONTROL 0x10