WINGs: remove macro ABS_SHIFT from the wcolorpanel code

This macro was define a *very* long time ago, in commit
  d98f1fa645
but was not used at that time, and have never been used anywhere since
then.

As the macro does not look like a good idea for performance anyway, get rid
of it before anyone could get tempted to use it.

Signed-off-by: Christophe CURIS <christophe.curis@free.fr>

WINGs/wcolorpanel.c

@@ -3525,9 +3525,6 @@ static void convertCPColor(CPColor * color)
 	}
 }
 
-#define ABS_SHIFT(val, shift) \
-    (((shift) > 0) ? (val) >> (shift) : (val) << -(shift))
-
 static RColor ulongToRColor(WMScreen * scr, unsigned long value)
 {
 	RColor color;