Whoops, FreeBSD 6.2 doesn't define __FreeBSD_kernel_version

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%404027

src/joystick/bsd/SDL_sysjoystick.c

@@ -36,6 +36,10 @@
 #include <fcntl.h>
 #include <errno.h>
 
+#ifndef __FreeBSD_kernel_version
+#define __FreeBSD_kernel_version __FreeBSD_version
+#endif
+
 #if defined(HAVE_USB_H)
 #include <usb.h>
 #endif