DINPUT: Linux input FF effect stub implementation (FF #5)

[Daniel Remenak]

The fifth in a series of patches to enable force feedback through
DirectInput on linux event devices.

Changelog:
Stub a linux input system force feedback effect implementation

This is an example of an effect implementation which uses the
functions in FF #4.  Ultimately Start, Stop, GetEffectStatus,
Download, and Unload will need to be implemented in effect_linuxinput
in order for force feedback to actually feed back forcefully.

The architecture used by effect & effect_linuxinput mirrors that used
by device, joystick_linux, joystick_linuxinput etc, to allow for other
force feedback implementations (e.g. osx/intel, alternate linux
implementations, whoever else) to easily reuse code for
system-independent functions like SetParameters and GetParameters,
object overhead, miscellaneous helpers, stubs for non-implemented
functions, and debug ouput functions, which are in effect.c (like
device.c).

This patch adds one more file, effect_linuxinput.c, in the
dlls/dinput directory.  This patch depends on FF #4 in order to
compile.