GAME: Fix a warning about different function prototype

Apparently, for MSVC, int foo() is not the same as int foo(void)...

src/game/joystick_ch_flightstick_pro.c

@@ -47,7 +47,7 @@
 #include "joystick_standard.h"
 
 
-static void *ch_flightstick_pro_init()
+static void *ch_flightstick_pro_init(void)
 {
 	return NULL;
 }

src/game/joystick_standard.c

@@ -47,7 +47,7 @@
 #include "joystick_standard.h"
 
 
-static void *joystick_standard_init()
+static void *joystick_standard_init(void)
 {
 	return NULL;
 }

src/game/joystick_sw_pad.c

@@ -126,7 +126,7 @@ static int sw_parity(uint16_t data)
         return bits_set & 1;
 }
 
-static void *sw_init()
+static void *sw_init(void)
 {
         sw_data *sw = (sw_data *)malloc(sizeof(sw_data));
         memset(sw, 0, sizeof(sw_data));