Bug 7440: Stub implementation of LLVM tablegen multi-class syntax

Implements just enough of the TableGen multi-class syntax to parse
current versions of the llvm/IR/Intrinsics.td sources.

* sources/app/llvm-tablegen/tablegen-multi-class.dylan
  (<tablegen-multi-class>): New class.

* sources/app/llvm-tablegen/llvm-tablegen.lid:
  Reference tablegen-multi-class.dylan.

* sources/app/llvm-tablegen/tablegen-parser.dylgram
  (class-reference-class): Allow multi-class references.
  (object rules): Implement scopes as thunks. Ignore defm definitions.
  (class-inst rules): Implement class as a thunk.
  (def-inst rules): Implement def as a thunk. Prepend thunk-passed prefix
   to defined rules.
  (multi-class-inst, multi-class-name, multi-class-body rules):
   Parse multiclass definitions.
  (defm-inst rules): Rename from def-minst.
Bug 7440: Improve LLVM intrinsic generation

* sources/app/llvm-tablegen/tablegen-intrinsics.dylan
  (llvm-type-vector?): New method for identifying vector types.
  ($valuetype-map): Add mapping for x86mmx.
  (tablegen-gen-intrinsic): Improve logic for deciding whether or not to
   include an intrinsic in the output mapping.
Bug 7440: Re-generate intrinsics from current (3.4svn) sources