Fix the NaCl bitstream reader to report fatal errors.

lib/Bitcode/NaCl/Reader/NaClBitcodeReader.cpp

 //===- NaClBitcodeReader.cpp ----------------------------------------------===//
 //     Internal NaClBitcodeReader implementation
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
@@ skipping 1828 matching lines @@
 }
 
 std::error_code NaClBitcodeReader::InitStreamFromBuffer() {
   const unsigned char *BufPtr = (const unsigned char*)Buffer->getBufferStart();
   const unsigned char *BufEnd = BufPtr+Buffer->getBufferSize();
 
   if (Buffer->getBufferSize() & 3)
     return Error(InvalidBitstream,
                  "Bitcode stream should be a multiple of 4 bytes in length");
 
-  if (Header.Read(BufPtr, BufEnd))
+  const unsigned char *HeaderPtr = BufPtr;
+  if (Header.Read(HeaderPtr, BufEnd))
     return Error(InvalidBitstream, Header.Unsupported());
 
-  StreamFile.reset(new NaClBitstreamReader(BufPtr, BufEnd));
+  StreamFile.reset(new NaClBitstreamReader(BufPtr, BufEnd,
+                                           Header.getHeaderSize()));
   Stream.init(StreamFile.get());
 
   if (AcceptHeader())
     return Error(InvalidBitstream, Header.Unsupported());
   return std::error_code();
 }
 
 std::error_code NaClBitcodeReader::InitLazyStream() {
   if (Header.Read(LazyStreamer))
     return Error(InvalidBitstream, Header.Unsupported());
@@ skipping 72 matching lines @@
   if (std::error_code EC = M->materializeAllPermanently()) {
     delete M;
     return EC;
   }
 
   // TODO: Restore the use-lists to the in-memory state when the bitcode was
   // written.  We must defer until the Module has been fully materialized.
 
   return M;
 }