[pr19844] Add thread local mode to aliases.

This matches gcc's behavior. It also seems natural given that aliases
contain other properties that govern how it is accessed (linkage,
visibility, dll storage).

Clang still has to be updated to expose this feature to C.

llvm-svn: 209759

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -2017,6 +2017,8 @@ error_code BitcodeReader::ParseModule(bool Resume) {
         NewGA->setDLLStorageClass(GetDecodedDLLStorageClass(Record[4]));
       else
         UpgradeDLLImportExportLinkage(NewGA, Record[2]);
+      if (Record.size() > 5)
+	NewGA->setThreadLocalMode(GetDecodedThreadLocalMode(Record[5]));
       ValueList.push_back(NewGA);
       AliasInits.push_back(std::make_pair(NewGA, Record[1]));
       break;