Use std::move so this code compiles properly using gcc.

R=dsinclair@chromium.org

Bug:
Change-Id: I34f9498f4e5942c5b10ab2848509de935882321d
Reviewed-on: https://pdfium-review.googlesource.com/13470
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
diff --git a/core/fxcrt/xml/cfx_xmlelement.cpp b/core/fxcrt/xml/cfx_xmlelement.cpp
index e72b77c..5b5fe45 100644
--- a/core/fxcrt/xml/cfx_xmlelement.cpp
+++ b/core/fxcrt/xml/cfx_xmlelement.cpp
@@ -6,6 +6,8 @@
 
 #include "core/fxcrt/xml/cfx_xmlelement.h"
 
+#include <utility>
+
 #include "core/fxcrt/cfx_widetextbuf.h"
 #include "core/fxcrt/fx_extension.h"
 #include "core/fxcrt/xml/cfx_xmlchardata.h"
@@ -39,7 +41,7 @@
     pChild = pChild->m_pNext;
   }
   pClone->SetTextData(wsText);
-  return pClone;
+  return std::move(pClone);
 }
 
 CFX_WideString CFX_XMLElement::GetLocalTagName() const {
diff --git a/core/fxcrt/xml/cfx_xmlinstruction.cpp b/core/fxcrt/xml/cfx_xmlinstruction.cpp
index 6886172..3c7deda 100644
--- a/core/fxcrt/xml/cfx_xmlinstruction.cpp
+++ b/core/fxcrt/xml/cfx_xmlinstruction.cpp
@@ -6,6 +6,8 @@
 
 #include "core/fxcrt/xml/cfx_xmlinstruction.h"
 
+#include <utility>
+
 #include "core/fxcrt/fx_extension.h"
 #include "third_party/base/ptr_util.h"
 #include "third_party/base/stl_util.h"
@@ -23,7 +25,7 @@
   auto pClone = pdfium::MakeUnique<CFX_XMLInstruction>(GetName());
   pClone->SetAttributes(GetAttributes());
   pClone->m_TargetData = m_TargetData;
-  return pClone;
+  return std::move(pClone);
 }
 
 void CFX_XMLInstruction::AppendData(const CFX_WideString& wsData) {