SIOCGIFXMEDIA values on other FreeBSD architectures

[clausecker]

Greetings!

I would like to report the following SIOCGIFXMEDIA values on other FreeBSD architectures to improve the portability of this crate:

• armv7: 0xc028698b
• aarch64: 0xc030698b
• powerpc64le: 0xc030698b

Additionally, it would be nice to have a generic fallback on unknown platforms so that the code always builds.

[pkubaj]

I just saw this issue linked from FreeBSD commit mail, your commit is missing powerpc64, which my PR also fixes #169

[clausecker]

@pkubaj Feel free to amend my patch. Note that yours does not cover armv7.

[shellrow]

Thanks for reporting this and for providing the values for the additional FreeBSD architectures.

I just merged #169 first, since it addresses the existing 64-bit FreeBSD assumption.

I'll use the information from this issue to further improve portability across FreeBSD architectures.

[clausecker]

@shellrow You can simply add the armv7 case to #169 and everything should be covered. It's different from the i386 case as time_t is 64 bits on armv7 FreeBSD.