Handle some renamed ThinLTO functions

Author: alexcrichton

src/rustllvm/PassWrapper.cpp

@@ -953,7 +953,11 @@ LLVMRustCreateThinLTOData(LLVMRustThinLTOModule *modules,
                               GlobalValue::LinkageTypes NewLinkage) {
     ResolvedODR[ModuleIdentifier][GUID] = NewLinkage;
   };
+#if LLVM_VERSION_GE(8, 0)
+  thinLTOResolvePrevailingInIndex(Ret->Index, isPrevailing, recordNewLinkage);
+#else
   thinLTOResolveWeakForLinkerInIndex(Ret->Index, isPrevailing, recordNewLinkage);
+#endif
 
   // Here we calculate an `ExportedGUIDs` set for use in the `isExported`
   // callback below. This callback below will dictate the linkage for all
@@ -1016,7 +1020,11 @@ extern "C" bool
 LLVMRustPrepareThinLTOResolveWeak(const LLVMRustThinLTOData *Data, LLVMModuleRef M) {
   Module &Mod = *unwrap(M);
   const auto &DefinedGlobals = Data->ModuleToDefinedGVSummaries.lookup(Mod.getModuleIdentifier());
+#if LLVM_VERSION_GE(8, 0)
+  thinLTOResolvePrevailingInModule(Mod, DefinedGlobals);
+#else
   thinLTOResolveWeakForLinkerModule(Mod, DefinedGlobals);
+#endif
   return true;
 }