Bug #:

Submitted by:
Reviewed by:
Add three new classes to Decl.h: BlockVarDecl, FileVarDecl, and ParmVarDecl.

Made the constructor to VarDecl protected, to indicate it is "abstract".

Reorganized the Decl::Kind enum to allow us to add ObjectDecls/TypeDecls with
minimal breakage.  In the process, realized the isa support for ObjectDecl was already broken (so
the reorg paid for itself already:-) The range check should also be more efficient...

llvm-svn: 39373