PPC: [turbofan] Add an InterpreterDispatch linkage type.

Port a0129a25

R=rmcilroy@chromium.org, dstence@us.ibm.com, michael_dawson@ca.ibm.com
BUG=

Review URL: https://codereview.chromium.org/1232803004

Cr-Commit-Position: refs/heads/master@{#29620}

src/compiler/ppc/instruction-selector-ppc.cc

@@ -1547,6 +1547,7 @@ void InstructionSelector::VisitTailCall(Node* node) {
     InstructionCode opcode;
     switch (descriptor->kind()) {
       case CallDescriptor::kCallCodeObject:
+      case CallDescriptor::kInterpreterDispatch:
         opcode = kArchTailCallCodeObject;
         break;
       case CallDescriptor::kCallJSFunction:

src/compiler/ppc/linkage-ppc.cc

@@ -67,6 +67,12 @@ CallDescriptor* Linkage::GetSimplifiedCDescriptor(Zone* zone,
   return LH::GetSimplifiedCDescriptor(zone, sig);
 }
 
+
+CallDescriptor* Linkage::GetInterpreterDispatchDescriptor(
+    Zone* zone, const MachineSignature* sig) {
+  return LH::GetInterpreterDispatchDescriptor(zone, sig);
+}
+
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8