Cleanup: remove redundant, invalid info from headers

BF-admins agree to remove header information that isn't useful,
to reduce noise.

- BEGIN/END license blocks

  Developers should add non license comments as separate comment blocks.
  No need for separator text.

- Contributors

  This is often invalid, outdated or misleading
  especially when splitting files.

  It's more useful to git-blame to find out who has developed the code.

See P901 for script to perform these edits.

source/blender/editors/interface/interface_eyedropper_depth.c

@@ -1,6 +1,4 @@
 /*
- * ***** BEGIN GPL LICENSE BLOCK *****
- *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version 2
@@ -17,8 +15,6 @@
  *
  * The Original Code is Copyright (C) 2009 Blender Foundation.
  * All rights reserved.
- *
- * ***** END GPL LICENSE BLOCK *****
  */
 
 /** \file blender/editors/interface/interface_eyedropper_depth.c
@@ -155,7 +151,6 @@ static void depthdropper_exit(bContext *C, wmOperator *op)
 /* *** depthdropper id helper functions *** */
 /**
  * \brief get the ID from the screen.
- *
  */
 static void depthdropper_depth_sample_pt(bContext *C, DepthDropper *ddr, int mx, int my, float *r_depth)
 {