Merging r168354, r168355 and r168379 into the 3.2 release branch.

Set of  Attributes patches.

Merging r168354:

Make the AttrListPtr object a part of the LLVMContext.

When code deletes the context, the AttributeImpls that the AttrListPtr points to
are now invalid. Therefore, instead of keeping a separate managed static for the
AttrListPtrs that's reference counted, move it into the LLVMContext and delete
it when deleting the AttributeImpls.

Merging r168355:

Merging r168379

git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_32@168457 91177308-0d34-0410-b5e6-96231b3b80d8

utils/TableGen/IntrinsicEmitter.cpp

@@ -621,7 +621,7 @@ EmitAttributes(const std::vector<CodeGenIntrinsic> &Ints, raw_ostream &OS) {
   
   OS << "    }\n";
   OS << "  }\n";
-  OS << "  return AttrListPtr::get(ArrayRef<AttributeWithIndex>(AWI, "
+  OS << "  return AttrListPtr::get(C, ArrayRef<AttributeWithIndex>(AWI, "
              "NumAttrs));\n";
   OS << "}\n";
   OS << "#endif // GET_INTRINSIC_ATTRIBUTES\n\n";