Auto merge of #2010 - tamird:if-namsiz, r=JohnTitor
Auto merge of #2010 - tamird:if-namsiz, r=JohnTitor

Define IFNAMSIZ for Fuchsia

https://cs.opensource.google/fuchsia/fuchsia/+/master:zircon/third_party/ulib/musl/include/net/if.h;l=72;drc=bdf60afa9193c8a9190ee6bb6b5a0a11ad8876b6

rust-lang/libc,rust-lang/libc,rust-lang/libc