XFA: Needless include in pdfppo.cpp

R=thestig@chromium.org
TBR=thestig@chromium.org

Review URL: https://codereview.chromium.org/1477983002 .
diff --git a/fpdfsdk/src/fpdfppo.cpp b/fpdfsdk/src/fpdfppo.cpp
index 6ae6531..507b97b 100644
--- a/fpdfsdk/src/fpdfppo.cpp
+++ b/fpdfsdk/src/fpdfppo.cpp
@@ -6,7 +6,6 @@
 
 #include "public/fpdf_ppo.h"
 
-#include "../include/fpdfxfa/fpdfxfa_doc.h"
 #include "fpdfsdk/include/fsdk_define.h"
 #include "third_party/base/nonstd_unique_ptr.h"