You do know that you can relicense LGPL-2.1 code to GPL-2+?
"You may opt to apply the terms of the ordinary GNU General Public License instead of this License to a given copy of the Library. To do this, you must alter all the notices that refer to this License, so that they refer to the ordinary GNU General Public License, version 2, instead of to this License. (If a newer version than version 2 of the ordinary GNU General Public License has appeared, then you can specify that version instead if you wish.) Do not make any other change in these notices."
The LGPL only specifies a minimum version of the GPL to relicense to, not a maximum. Thus, there is no problem at all.