Remove platform plugins from lldb-server

Summary:
This removes the last usage of Platform plugins in lldb-server -- it was used for launching child
processes, where it can be trivially replaced by Host::LaunchProces (as lldb-server is always
running on the host).

Removing platform plugins enables us to remove a lot of other unused code, which was pulled in as
a transitive dependency, and it reduces lldb-server size by 4%--9% (depending on build type and
architecture).

Reviewers: clayborg

Subscribers: tberghammer, danalbert, srhines, lldb-commits

Differential Revision: http://reviews.llvm.org/D20440

llvm-svn: 274125
diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.cpp b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.cpp
index eba237c..d6900c2 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.cpp
@@ -53,7 +53,6 @@
       m_socket_protocol(socket_protocol),
       m_socket_scheme(socket_scheme),
       m_spawned_pids_mutex(),
-      m_platform_sp(Platform::GetHostPlatform()),
       m_port_map(),
       m_port_offset(0)
 {
@@ -463,7 +462,7 @@
             std::bind(&GDBRemoteCommunicationServerPlatform::DebugserverProcessReaped, this, std::placeholders::_1),
             false);
 
-    Error error = m_platform_sp->LaunchProcess (m_process_launch_info);
+    Error error = Host::LaunchProcess(m_process_launch_info);
     if (!error.Success ())
     {
         fprintf (stderr, "%s: failed to launch executable %s", __FUNCTION__, m_process_launch_info.GetArguments ().GetArgumentAtIndex (0));