Change License of versioninfo.rc.in to GPL

To avoid headaches with the previous non standard permissive
license we change it explicity to GPL to be in line with the rest
of the code.

(cherry picked from commit 6eed22e67442aae24c4f7df4d4d4572c7edf76a6)

• Signed-off-by: Andre Heinecke <aheinecke@intevation.de>