Fix Solaris cross-build job

[newpavlov]

It fails with linker error, e.g. see: https://github.com/rust-random/getrandom/runs/5698849705

Relevant Rust issue: rust-lang/rust#94052

It looks like due to libc changes we now need Solaris-specific sendfile and lgrp.

[josephlr]

Fixed by #301