This issue occured when attempt to build the v0.8.9 release with go1.14.4. The build succeeded for go1.13.
To reproduce:
$ GOOS=solaris GOARCH=amd64 go build ./...
syscall.Syscall6·f: relocation target syscall.Syscall6 not defined
Expected: no error.
It seems to be related to golang/go#24357 where Syscall6 seems to be declared but not implemented. As syscall package is locked down, a fix may not be available from golang/go.
A possible solution is to have an ignore list in goexports to skip symbols known to be unavailable, or to skip entirely the solaris platform.