netlink: Forward declare frequent libnl types to ease inclusion deps
netlink: Forward declare frequent libnl types to ease inclusion deps

Signed-off-by: Thomas Graf <17c2d8920621522552b392f72d8fdb4d1e866b44@suug.ch>

HolyShitMan/libnl-1,cyclops8456/libnl3,honsys/libnl,baloo/libnl,baloo/libnl,karlhiramoto/libnl,UnicronNL/libnl3,teto/libnl_old,vyos/libnl3,karlhiramoto/libnl,tklauser/libnl,baloo/libnl,chitranshi/libnl,UnicronNL/libnl3,dsahern/libnl,dsahern/libnl,congwang/libnl,tgraf/libnl,claudelee/libnl,honsys/libnl,tklauser/libnl,thom311/libnl,Distrotech/libnl,UnicronNL/libnl3,vyos/libnl3,teto/libnl_old,claudelee/libnl,cyclops8456/libnl3,thom311/libnl,chitranshi/libnl,cyclops8456/libnl3,greearb/libnl-ct,houstar/libnl,dsahern/libnl,honsys/libnl,tgraf/libnl,vyos/libnl3,cfriedt/libnl,cfriedt/libnl,Distrotech/libnl,houstar/libnl,houstar/libnl,greearb/libnl-ct,houstar/libnl,mshirley/libnl,honsys/libnl,teto/libnl_old,HolyShitMan/libnl-1,HolyShitMan/libnl-1,mshirley/libnl,tklauser/libnl,baloo/libnl,greearb/libnl-ct,kolyshkin/libnl,congwang/libnl,congwang/libnl,teto/libnl_old,congwang/libnl,cyclops8456/libnl3,chitranshi/libnl,Distrotech/libnl,chitranshi/libnl,cfriedt/libnl,karlhiramoto/libnl,vyos/libnl3,dsahern/libnl,cfriedt/libnl,tgraf/libnl,Distrotech/libnl,HolyShitMan/libnl-1,mshirley/libnl,thom311/libnl,kolyshkin/libnl,tklauser/libnl,kolyshkin/libnl,claudelee/libnl,tgraf/libnl,kolyshkin/libnl,claudelee/libnl,karlhiramoto/libnl,UnicronNL/libnl3,mshirley/libnl