Fix tzHour usage on systems where char is unsigned.

fpdfsdk/include/fsdk_baseannot.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 _FSDK_BASEANNOT_H_
 #define _FSDK_BASEANNOT_H_
 
 #if _FX_OS_ == _FX_ANDROID_
@@ skipping 35 matching lines @@
         void                            ResetDateTime();
         
         struct FX_DATETIME
         {
                 FX_SHORT        year;
                 FX_BYTE         month;
                 FX_BYTE         day;
                 FX_BYTE         hour;
                 FX_BYTE         minute;
                 FX_BYTE         second;
-                FX_CHAR         tzHour;
+                FX_INT8         tzHour;
                 FX_BYTE         tzMinute;
         }dt;
 };
 
 class CPDFSDK_Annot
 {
 public:
         CPDFSDK_Annot(CPDF_Annot* pAnnot, CPDFSDK_PageView* pPageView);
         virtual ~CPDFSDK_Annot();
 public:
@@ skipping 109 matching lines @@
         CPDFSDK_PageView*       m_pPageView;
         FX_BOOL                         m_bSelected;
         int                                     m_nTabOrder;
         
 };
 
 
 
 #endif