Make a major API change to BitstreamReader: split all the reading

state out of the BitstreamReader class into a BitstreamCursor class.
Doing this allows the client to have multiple cursors into the same
file, each with potentially different live block stacks and
abbreviation records.

llvm-svn: 70157

llvm/lib/Bitcode/Reader/BitcodeReader.h

@@ -86,7 +86,8 @@ public:
 
 class BitcodeReader : public ModuleProvider {
   MemoryBuffer *Buffer;
-  BitstreamReader Stream;
+  BitstreamReader StreamFile;
+  BitstreamCursor Stream;
   
   const char *ErrorString;