remove now all the files fro depot for PDF API since we generate them at build time

experimental/PdfViewer/pdfparser/podofo/autogen/SkPdfHexString_autogen.h

-#ifndef __DEFINED__SkPdfHexString
-#define __DEFINED__SkPdfHexString
-
-#include "SkPdfUtils.h"
-#include "SkPdfEnums_autogen.h"
-#include "SkPdfArray_autogen.h"
-#include "SkPdfString_autogen.h"
-
-class SkPdfHexString : public SkPdfString {
-public:
-  virtual SkPdfObjectType getType() const { return kHexString_SkPdfObjectType;}
-  virtual SkPdfObjectType getTypeEnd() const { return (SkPdfObjectType)(kHexString_SkPdfObjectType + 1);}
-public:
-  virtual SkPdfHexString* asHexString() {return this;}
-  virtual const SkPdfHexString* asHexString() const {return this;}
-
-private:
-public:
-  const std::string& value() const {return fPodofoObj->GetString().GetStringUtf8();}
-private:
-public:
-  SkPdfHexString(const PdfMemDocument* podofoDoc = NULL, const PdfObject* podofoObj = NULL) : SkPdfString(podofoDoc, podofoObj) {}
-
-  SkPdfHexString(const SkPdfHexString& from) : SkPdfString(from.fPodofoDoc, from.fPodofoObj) {}
-
-  virtual bool valid() const {return true;}
-
-  SkPdfHexString& operator=(const SkPdfHexString& from) {this->fPodofoDoc = from.fPodofoDoc; this->fPodofoObj = from.fPodofoObj; return *this;}
-
-};
-
-#endif  // __DEFINED__SkPdfHexString