Commit For New Tool: llvm-abcd (Analysis of ByteCode Dumper). This tool

Commit For New Tool: llvm-abcd (Analysis of ByteCode Dumper).  This tool
will (eventually) provide statistical analysis of bytecode files as well
as the ability to dump them in a low level format (slot numbers not
resolved). The purpose of this is to aid in the Type!=Value change of
bug 122. With this initial release, llvm-abcd merely dumps out the
bytecode. However, the infrastructure for separating bytecode parsing from
handling the parsing events is in place. The style chosen is similar to
SAX XML parsing where a handler object is called to handlign the parsing
events. This probably isn't useful to anyone but me right now as there is
no analysis yet, and the dumper doesn't work on every bytecode file. It
will probably be useful by the end of this week. Note that there is some
duplication of code from the bytecode reader.  This was done to eliminate
errors from being introduced in the reader and to minimize the impact to
other LLVM developers. At some point, the Analyzer and the Reader will be
integrated to use the same infrastructure. Also, sorry for the minor change
to Instruction.h but I just couldn't bring myself to write code that
depends on Instruction internals.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@14048 91177308-0d34-0410-b5e6-96231b3b80d8