Fix DSU joystick build on Unix platforms

Add missing sys/time.h for struct timeval and sys/select.h for select()
function and fd_set types. These headers are required for socket operations
on Unix-like platforms including Linux, BSD, and other POSIX systems.

This resolves compilation errors:
- 'storage size of tv isn't known' (struct timeval)
- 'implicit declaration of function select'
- 'fd_set' and related macros undeclared

The headers are added to the standard Unix/Linux platform section
after errno.h and before sys/ioctl.h to maintain proper ordering.

src/joystick/dsu/SDL_dsujoystick.c

@@ -88,6 +88,8 @@ typedef int socklen_t;
         #include <fcntl.h>
         #include <unistd.h>
         #include <errno.h>
+        #include <sys/time.h>
+        #include <sys/select.h>
         #ifdef HAVE_SYS_IOCTL_H
             #include <sys/ioctl.h>
         #endif