macosx: fix fullscreen volume slider knob alignment

(cherry picked from commit bd994203590f11a8cad6c992171036553c450593)

modules/gui/macosx/fspanel.m

@@ -450,7 +450,7 @@
     /* volume slider */
     s_rc = [self frame];
     s_rc.origin.x = 26;
-    s_rc.origin.y = 20;
+    s_rc.origin.y = 21;
     s_rc.size.width = 95;
     s_rc.size.height = 10;
     o_fs_volumeSlider = [[VLCFSVolumeSlider alloc] initWithFrame: s_rc];
@@ -682,7 +682,7 @@
     [[NSGraphicsContext currentContext] restoreGraphicsState];
 
     NSRect knobRect = [[self cell] knobRectFlipped:NO];
-    knobRect.origin.y+=6;
+    knobRect.origin.y+=7.5;
     [[[NSColor blackColor] colorWithAlphaComponent:0.6] set];
     [self drawKnobInRect: knobRect];
 }