Whoops, FreeBSD 6.2 doesn't define __FreeBSD_kernel_version

--HG--
branch : SDL-1.2

src/joystick/bsd/SDL_sysjoystick.c

@@ -36,6 +36,11 @@
 #include <fcntl.h>
 #include <errno.h>
 
+#include <sys/param.h>
+#ifndef __FreeBSD_kernel_version
+#define __FreeBSD_kernel_version __FreeBSD_version
+#endif
+
 #if defined(HAVE_USB_H)
 #include <usb.h>
 #endif