macosx: fix time slider knob alignment in bright mode

(cherry picked from commit 4caa39f04d760998a057a2d6affbbdad6c6f3c4a)

modules/gui/macosx/misc.m

@@ -548,8 +548,6 @@ void _drawFrameInRect(NSRect frameRect)
     NSRect knobRect = [[self cell] knobRectFlipped:NO];
     if (b_dark)
         knobRect.origin.y+=2;
-    else
-        knobRect.origin.y+=1;
     [self drawKnobInRect: knobRect];
 }