Fix socket leak in lldb-server platform

lldb-server server process was holding on to a connection to every
client that connected. This continued until the process hit it's
file limit and exited.

lldb-server p --listen *:5432 --server

run remote tests against that server more than 1000 times

Differential Revision: http://reviews.llvm.org/D8697

llvm-svn: 233651