in the attempt to fix 627393, changed IFX_FileRead's readBlock to return the length it reads

core/fxcrt/fx_stream.h

Index: core/fxcrt/fx_stream.h
diff --git a/core/fxcrt/fx_stream.h b/core/fxcrt/fx_stream.h
index dc687cf65331f915dadd56bda224f05297593636..9bf5f6965cafaf3f9da78c3d51043c529892fc94 100644
--- a/core/fxcrt/fx_stream.h
+++ b/core/fxcrt/fx_stream.h
@@ -91,7 +91,7 @@ class IFX_SeekableReadStream : public IFX_ReadStream {
   FX_FILESIZE GetPosition() override;
   size_t ReadBlock(void* buffer, size_t size) override;
 
-  virtual bool ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) = 0;
+  virtual size_t ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) = 0;
   virtual FX_FILESIZE GetSize() = 0;
 };
 
@@ -108,7 +108,7 @@ class IFX_SeekableStream : public IFX_SeekableReadStream,
   bool IsEOF() override = 0;
   FX_FILESIZE GetPosition() override = 0;
   size_t ReadBlock(void* buffer, size_t size) override = 0;
-  bool ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) override = 0;
+  size_t ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) override = 0;
   FX_FILESIZE GetSize() override = 0;
 
   // IFX_SeekableWriteStream: