[Driver][OpenMP] Update actions builder to create bundling action when necessary.

Summary:
In order to save the user from dealing with multiple output files (for host and device) while using separate compilation, a new action `OffloadBundlingAction` is used when the last phase is not linking. This action will then result in a job that uses the proposed bundling tool to create a single preprocessed/IR/ASM/Object file from multiple ones.

The job creation for the new action will be proposed in a separate patch.

Reviewers: echristo, tra, jlebar, ABataev, hfinkel

Subscribers: whchung, mehdi_amini, cfe-commits, Hahnfeld, andreybokhanko, arpith-jacob, carlo.bertolli, caomhin

Differential Revision: https://reviews.llvm.org/D21852

llvm-svn: 285323
diff --git a/clang/lib/Driver/Action.cpp b/clang/lib/Driver/Action.cpp
index a351429..90bc149 100644
--- a/clang/lib/Driver/Action.cpp
+++ b/clang/lib/Driver/Action.cpp
@@ -36,6 +36,8 @@
   case DsymutilJobClass: return "dsymutil";
   case VerifyDebugInfoJobClass: return "verify-debug-info";
   case VerifyPCHJobClass: return "verify-pch";
+  case OffloadBundlingJobClass:
+    return "clang-offload-bundler";
   }
 
   llvm_unreachable("invalid class");
@@ -346,3 +348,8 @@
 
 VerifyPCHJobAction::VerifyPCHJobAction(Action *Input, types::ID Type)
     : VerifyJobAction(VerifyPCHJobClass, Input, Type) {}
+
+void OffloadBundlingJobAction::anchor() {}
+
+OffloadBundlingJobAction::OffloadBundlingJobAction(ActionList &Inputs)
+    : JobAction(OffloadBundlingJobClass, Inputs, Inputs.front()->getType()) {}