Update subzero bitcode parser to use new API for bitstream reading.

src/PNaClTranslator.cpp

Index: src/PNaClTranslator.cpp
diff --git a/src/PNaClTranslator.cpp b/src/PNaClTranslator.cpp
index 42a207b510bafb456cdf9b3f1351aa22afc68a74..38c5bf71c14d43f8a14691e80a7b8601ba569ff4 100644
--- a/src/PNaClTranslator.cpp
+++ b/src/PNaClTranslator.cpp
@@ -2995,7 +2995,7 @@ void PNaClTranslator::translate(const std::string &IRFilename,
   }
 
   // Create a bitstream reader to read the bitcode file.
-  NaClBitstreamReader InputStreamFile(MemObj.release(), Header.getHeaderSize());
+  NaClBitstreamReader InputStreamFile(MemObj.release(), Header);
   NaClBitstreamCursor InputStream(InputStreamFile);
 
   TopLevelParser Parser(*this, InputStream, ErrorStatus);