Fix __serial.h for both Win32 and non-Win32

src/boards/__serial.h

@@ -3,7 +3,6 @@
 
 #include <stdio.h>
 
-#ifdef _WIN32
 typedef int BOOL;
 
 #ifndef TRUE
@@ -14,8 +13,6 @@ typedef int BOOL;
 #define FALSE 0
 #endif
 
-#endif
-
 #include "../fceu-types.h"
 
 void SendCmd(uint8 *cmd, int size);