Major update of llvm-upgrade:

1. Completely revise the type system so that types are handled as const
   objects and not created multiple times, cloned, or otherwise copied.
   This gets around memory issues, saves memory, and also emulates LLVM's
   no-two-types-of-the-same-shape-created semantics.
2. Adjust the handling of global names. Basically, we cannot rename them
   for a variety of reasons: linking, forward references, etc.
3. Detect global names that have name conflicts as the result of collapsed
   type planes or redefinitions that llvm-as no longer accepts. These will
   produce warnings on stderr and one of the globals will be renamed.
4. Rename ParserInternals.h as UpgradeInternals.h so it doesn't conflict
   in the debugger with ParserInternals.h from lib/AsmParser.
5. Move the guts of the TypeInfo class into the grammar so we aren't
   implementing large functions in a header file. This also helps with
   debugging a bit.

llvm-svn: 32906