hurd: Avoid warnings

[sthibaul]

The warning for line 37 was:

./pcap-hurd.c:196:35: warning: expression does not compute the number of elements in this array; element type is 'struct bpf_insn', not 'short' [-Wsizeof-array-div]
                          (filter_array_t_filter, FILTER_COUNT);
                                                  ^~~~~~~~~~~~

But device_set_filter really does want the size in units of shorts.

[infrastation]

How to get a functional Hurd VM:

1. Install VirtualBox and qemu-utils.
2. Download debian-hurd.img.tar.gz as shown on this page.
3. Extract the .img file from the tarball and convert it to a VirtualBox disk image:

   qemu-img convert -f raw -O vdi debian-hurd-20210812.img debian-hurd-20210812.vdi
   

4. Create a 32-bit VM and use the file as the disk.
5. Boot and log in as root with no password.
6. apt-get update; apt-get install git cmake flex bison autoconf clang libpcap-dev
7. Create and use an unprivileged user.
8. Clone the repositories and build as usual.

[infrastation]

I also have a few fixes for tcpdump, will commit shortly.

[infrastation]

Also, if the system has libdbus-1-dev installed (as a dependency of libpcap-dev, or otherwise), libpcap will not pass make check:

$ testprogs/findalldevstest
dbus-system
        Description: D-Bus system bus
        Flags:

dbus-session
        Description: D-Bus session bus
        Flags:

Error in pcap_lookupnet: SIOCGIFADDR: dbus-system: No such device

But that's a different bug.

[infrastation]

Any objections to merge these changes?

[fxlb]

Any objections to merge these changes?

It should be better to add the warning for L37 in the body on the commit message, like:

The warning for line 37 was:
<folded warning message>

[sthibaul]

Any objections to merge these changes?

It should be better to add the warning for L37 in the body on the commit message, like:

The warning for line 37 was:
<folded warning message>

done so

[fxlb]

Commit message updated with full warning (place parentheses ...).

[fxlb]

Any objections to merge these changes?

I have no more objections.

[infrastation]

Thank you.

[fxlb]

But that's a different bug.

Should an issue be created on this subject?

[infrastation]

#1269 it is.