Fix all relative includes to core.

fpdfsdk/include/fsdk_mgr.h

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #ifndef FPDFSDK_INCLUDE_FSDK_MGR_H_
 #define FPDFSDK_INCLUDE_FSDK_MGR_H_
 
 #include <map>
 
-#include "../../core/include/fpdftext/fpdf_text.h"
+#include "core/include/fpdftext/fpdf_text.h"
 #include "fsdk_actionhandler.h"
 #include "fsdk_annothandler.h"
 #include "fsdk_baseannot.h"
 #include "fsdk_baseform.h"
 #include "fsdk_common.h"
 #include "fsdk_define.h"
 #include "fx_systemhandler.h"
 #include "javascript/IJavaScript.h"
 #include "public/fpdf_formfill.h"
 #include "public/fpdf_fwlevent.h"  // cross platform keycode and events define.
@@ skipping 405 matching lines @@
     }
 
     if (nStartPos < m)
       QuickSort(nStartPos, m, bAscend, pCompare);
     if (nStopPos > m)
       QuickSort(m, nStopPos, bAscend, pCompare);
   }
 };
 
 #endif  // FPDFSDK_INCLUDE_FSDK_MGR_H_