libnet: Clean and upgrade (see below)

* libbnet upstream on packetfactor is dead
  using https://github.com/sam-github/libnet

 instead
* Move to version 1.1.5
* Dropped patches (not needed): support-uclibc, new-autotools
* Added LIC_FILES_CHKSUM
* Removed useless do_install_append, works automatically
* Not building statically anymore
* Should be compatible with old v1.1 versions

Signed-off-by: Michael Lippautz <michael.lippautz@gmail.com>
Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>