Don't #include FormatManager.h from Debugger.h

Debugger.h is a huge file that gets included everywhere, and
FormatManager.h brings in a ton of unnecessary stuff and doesn't
even use anything from it in the header.

llvm-svn: 231161
diff --git a/lldb/source/Commands/CommandObjectThread.cpp b/lldb/source/Commands/CommandObjectThread.cpp
index 199d16b..9c36334 100644
--- a/lldb/source/Commands/CommandObjectThread.cpp
+++ b/lldb/source/Commands/CommandObjectThread.cpp
@@ -18,6 +18,7 @@
 #include "lldb/lldb-private.h"
 #include "lldb/Core/State.h"
 #include "lldb/Core/SourceManager.h"
+#include "lldb/Core/ValueObject.h"
 #include "lldb/Host/Host.h"
 #include "lldb/Host/StringConvert.h"
 #include "lldb/Interpreter/CommandInterpreter.h"