Bug#320515: BITS_PER_LONG used unconditionally but defined only if __KERNEL__ is defined

[Petter Reinholdtsen <pere@hungry.com>]

This problem affect clanlib as well.  I'm trying to prepare an NMU to
get it to use the new C++ ABI, and ran into this compile error:

  Compiling Sources/Display/Input/X11/joystick_linux.cpp
  In file included from Sources/Display/Input/X11/joystick_linux.h:45,
                   from Sources/Display/Input/X11/joystick_linux.cpp:25:
  /usr/include/linux/joystick.h:142:2: error: #error Unexpected BITS_PER_LONG
  make: *** [Libs/Intermediate/joystick_linux.o] Error 1


The propsed patch solved the compile problem of
Sources/Display/Input/X11/joystick_linux.cpp.