tests: add a reproducer for an infinite loop in ndisc_handle_datagram
    
    =0  ndisc_router_parse (rt=0x60d000000110) at ../src/libsystemd-network/ndisc-router.c:126
    =1  0x000055555558dc67 in ndisc_handle_datagram (nd=0x608000000020, rt=0x60d000000110) at ../src/libsystemd-network/sd-ndisc.c:170
    =2  0x000055555558e65d in ndisc_recv (s=0x611000000040, fd=4, revents=1, userdata=0x608000000020) at ../src/libsystemd-network/sd-ndisc.c:233
    =3  0x00007ffff63913a8 in source_dispatch (s=0x611000000040) at ../src/libsystemd/sd-event/sd-event.c:3042
    =4  0x00007ffff6395eab in sd_event_dispatch (e=0x617000000080) at ../src/libsystemd/sd-event/sd-event.c:3455
    =5  0x00007ffff6396b12 in sd_event_run (e=0x617000000080, timeout=18446744073709551615) at ../src/libsystemd/sd-event/sd-event.c:3512
    =6  0x0000555555583f5c in LLVMFuzzerTestOneInput (data=0x6060000000e0 "\206", size=53) at ../src/fuzz/fuzz-ndisc-rs.c:422
    =7  0x0000555555586356 in main (argc=2, argv=0x7fffffffe3d8) at ../src/fuzz/fuzz-main.c:33
    
    (cherry picked from commit df30e78e02f653c9e6ee6677b7ccaea21d3dcd7d)
    
    Resolves: #1696224
    
    patch_name: 0149-tests-add-a-reproducer-for-an-infinite-loop-in-ndisc.patch
    present_in_specfile: true
    location_in_specfile: 149
    squash_commits: true