Auto merge of #2123 - Heliozoa:master, r=JohnTitor
Auto merge of #2123 - Heliozoa:master, r=JohnTitor

Define SO_INCOMING_CPU for i686-unknown-linux-gnu

Hi! Following the example from #2119, I've tried adding the constant to i686-unknown-linux-gnu as well to fix a similar issue.

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