[IR] Add operand bundles to CallInst and InvokeInst.

Summary:
This change teaches `CallInst`s and `InvokeInst`s to maintain a set of
operand bundles as part of its operands.  `CallInst`s and `InvokeInst`s
with operand bundles co-allocate some space before their `Use` array to
hold meta information about which of its operands are part of an operand
bundle.

The strings corresponding to the bundle tags are interned into
`LLVMContextImpl::BundleTagCache`

This change does not include any parsing / bitcode support.  That's the
next change.

Depends on D12455.

Reviewers: reames, chandlerc, majnemer, dexonsmith, kmod, JosephTremoulet, rnk, bogner

Subscribers: MatzeB, sanjoy, llvm-commits

Differential Revision: http://reviews.llvm.org/D12456

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@248527 91177308-0d34-0410-b5e6-96231b3b80d8

lib/IR/Module.cpp

@@ -102,6 +102,9 @@ void Module::getMDKindNames(SmallVectorImpl<StringRef> &Result) const {
   return Context.getMDKindNames(Result);
 }
 
+void Module::getOperandBundleTags(SmallVectorImpl<StringRef> &Result) const {
+  return Context.getOperandBundleTags(Result);
+}
 
 //===----------------------------------------------------------------------===//
 // Methods for easy access to the functions in the module.