libpth: fix license info
NEWS states:
* Change license from LGPLv3+/GPLv2+ to LGPLv2+.
Fixes:
http://autobuild.buildroot.net/results/bef/
bef969ede5fc792b0a03f5669071600a0f746a7a/
http://autobuild.buildroot.net/results/2d5/
2d59b8e6d69b70c621ff2031a9c4fd9e67ef13cf/
http://autobuild.buildroot.net/results/631/
6318505c8e293e6c00b20eec39d851d0d15f6fec/
[Peter: also adjust _LICENSE, extend commit message]
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>