SO_INCOMING_CPU not defined for s390x-unknown-linux-gnu

[decathorpe]

I am trying to compile nb-connect 1.1.0 (which pulls in socket2 0.4.0) on Fedora Rawhide, but the build fails with SO_INCOMING_CPU not being defined in libc on i686 (fixed with libc 0.2.92) and s390x. I see that this constant was only very recently added to libc:

• Add SO_INCOMING_CPU for targets arm-unknown-linux-* #2115
• Define SO_INCOMING_CPU for {aarch64,x86_64}-unknown-linux-musl #2119
• Define SO_INCOMING_CPU for i686-unknown-linux-gnu #2123
• Define SO_INCOMING_CPU for i686-unknown-linux-musl #2124

But the constant has not been added to s390x-unknown-linux-gnu yet.