Fix clang build by removing unused locals.

Also don't manually set FD_CLOEXEC on a socket that's always opened
with SOCK_CLOEXEC. (None of the other callers to the function do this.)

Also move locals to where they're first used to help prevent more of this
kind of breakage.

Change-Id: I1ba7cd9400f53508dffb51a2bbf9d491ae647f26