Further reduce header footprint of Debugger.h.

llvm-svn: 231202
diff --git a/lldb/source/Target/Thread.cpp b/lldb/source/Target/Thread.cpp
index f127ae1..6f28a67 100644
--- a/lldb/source/Target/Thread.cpp
+++ b/lldb/source/Target/Thread.cpp
@@ -20,6 +20,8 @@
 #include "lldb/Core/RegularExpression.h"
 #include "lldb/Host/Host.h"
 #include "lldb/Interpreter/OptionValueFileSpecList.h"
+#include "lldb/Interpreter/OptionValueProperties.h"
+#include "lldb/Interpreter/Property.h"
 #include "lldb/Symbol/Function.h"
 #include "lldb/Target/ABI.h"
 #include "lldb/Target/DynamicLoader.h"