Relicense array, linked and tree based containers under LGPL?

[Bruno Haible]

Hi,

I would like to relicense the array, linked and tree based container modules
under LGPLv2+ (currently under GPL). The container modules based on hash
tables can stay under GPL, at least for the moment.

  list
  array-list
  carray-list
  linked-list
  avltree-list
  rbtree-list

  oset
  array-oset
  avltree-oset
  rbtree-oset

  omap
  array-omap
  avltree-omap
  rbtree-omap

The motivation is the new 'partial-function' module I'm working on, which
needs to depend on {avltree,rbtree}-list and {avltree,rbtree}-oset as
internal data structures. The array-*, carray-* and linked-list modules are
even simpler.

The rationale is that other implementations under LGPL exist:
  - For AVL trees: [1][2]
  - For red-black trees: [3]
For the array-*, carray-* and linked-list modules, there are surely plenty of
other implementations of the same algorithms under LGPL or MIT licenses.

The list of source files is

  lib/gl_anyavltree_list1.h
  lib/gl_anyavltree_list2.h
  lib/gl_anylinked_list1.h
  lib/gl_anylinked_list2.h
  lib/gl_anyrbtree_list1.h
  lib/gl_anyrbtree_list2.h
  lib/gl_anytree_list1.h
  lib/gl_anytree_list2.h
  lib/gl_anytree_omap.h
  lib/gl_anytree_oset.h
  lib/gl_array_list.c
  lib/gl_array_list.h
  lib/gl_array_omap.c
  lib/gl_array_omap.h
  lib/gl_array_oset.c
  lib/gl_array_oset.h
  lib/gl_avltree_list.c
  lib/gl_avltree_list.h
  lib/gl_avltree_omap.c
  lib/gl_avltree_omap.h
  lib/gl_avltree_ordered.h
  lib/gl_avltree_oset.c
  lib/gl_avltree_oset.h
  lib/gl_carray_list.c
  lib/gl_carray_list.h
  lib/gl_linked_list.c
  lib/gl_linked_list.h
  lib/gl_list.c
  lib/gl_list.h
  lib/gl_omap.c
  lib/gl_omap.h
  lib/gl_oset.c
  lib/gl_oset.h
  lib/gl_rbtree_list.c
  lib/gl_rbtree_list.h
  lib/gl_rbtree_omap.c
  lib/gl_rbtree_omap.h
  lib/gl_rbtree_ordered.h
  lib/gl_rbtree_oset.c
  lib/gl_rbtree_oset.h

They contain copyrightable changes by me, possibly copyrightable changes by
Paul Eggert, as well as tiny (not copyrightable) changes by Ralf Wildenhues,
Eric Blake, José Marchesi, Dylan Cali, Pádraig Brady, Akim Demaille.

Paul, would you agree to this change?

Bruno

[1] 
https://167.88.152.253/dmitchell/push-test/tree/7ad87dbf441b9d7df5ec51dd038f7fd1e9e6652a/src/avl
[2] http://www.mission-base.com/peter/source/pbl/doc/set.html
[3] https://github.com/c-util/c-rbtree