libnet: update version to 1.1.6

Changes:
- use doc/COPYING instead of README as the license file
- use BPN instead of PN to fix multilib build
- rebase the fix-endianess-test.patch

Signed-off-by: Jackie Huang <jackie.huang@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>