Increate backlog of lldb-platform's listener socket

lldb-platform's listener socket only had a backlog of one connection.
That means that if more than one client connected simultaneously, the
connection would be refused. The test suite can be run remotely with
dozens of threads connecting simultaneously. Raised this limit to 100
to effectively eliminate lost connections.

Test Plan:
run tests against a remote target

Differential Revision: http://reviews.llvm.org/D8696

llvm-svn: 233652
diff --git a/lldb/tools/lldb-server/lldb-platform.cpp b/lldb/tools/lldb-server/lldb-platform.cpp
index 47007ba..2135633 100644
--- a/lldb/tools/lldb-server/lldb-platform.cpp
+++ b/lldb/tools/lldb-server/lldb-platform.cpp
@@ -253,7 +253,12 @@
     Socket *socket = nullptr;
     printf ("Listening for a connection from %s...\n", listen_host_port.c_str());
     const bool children_inherit_listen_socket = false;
-    error = Socket::TcpListen(listen_host_port.c_str(), children_inherit_listen_socket, socket, NULL);
+
+    // the test suite makes many connections in parallel, let's not miss any.
+    // The highest this should get reasonably is a function of the number 
+    // of target CPUs.  For now, let's just use 100
+    const int backlog = 100;
+    error = Socket::TcpListen(listen_host_port.c_str(), children_inherit_listen_socket, socket, NULL, backlog);
     if (error.Fail())
     {
         printf("error: %s\n", error.AsCString());