fix up r354804, link zstreamdump with libzfs

Since r354804 libzpool depends on libzfs for get_system_hostid symbol.
Except for zstreamdump, all binaries linked with libzpool were already
linked with libzfs. So, zstreamdump is the only fall-out.

It's interesting that on amd64 not only I was able to successfully build
zstreamdump, I am able to run it despite having the unresolved symbol in
libzpool.

MFC after: 4 weeks
X-MFC with: r354804