Fix SunOS Builds broken sometime after 3.5.2 and by 3.7.1

Part of this is because an apparent attempt to not use libuv on SunOS appears to have equated "sparc" with "SunOS" thus leaving out Intel-based SunOS systems.

The other issue is that Solaris 11 requires explicit linking of -lsocket for some of the symbols in SystemInformation.cxx to be resolved. But perhaps there was somewhere else I should have put that to be a link library for all targets by default, but instead I put it at the lowest granularity for the need I found (as a target_link_library of libkwsys.a).

By the way, this is my first submission in the new GitLab regime, so let me know if I'm not doing the process correctly :-)