Fix socket leak in lldb-server platform

[vharron]

Summary

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.

[tberghammer]

LGTM

[flackr]

LGTM thanks

[clayborg]

Looks good.

tools/lldb-server/lldb-platform.cpp

do {
         }
         printf ("Connection established.\n");
         if (g_server)
         {
             // Collect child zombie processes.
             while (waitpid(-1, nullptr, WNOHANG) > 0);
             if (fork())
             {
+                // Parent doesn't need a connection to the lldb client
+                delete socket;
+                socket = nullptr;
+
                 // Parent will continue to listen for new connections.
                 continue;
             }
             else
             {
                 // Child process will handle the connection and exit.
                 g_server = 0;
                 // Listening socket is owned by parent process.