Explicitly move from llvm::json Array/Object to Value

[MForster]

Summary

The implicit conversion fails under Clang 3.8.

[sammccall]

Thanks!

clang-tools-extra/clangd/Protocol.cpp

static llvm::json::Value encodeTokens(llvm::ArrayRef<SemanticToken> Toks) {
   for (const auto &Tok : Toks) {
     Result.push_back(Tok.deltaLine);
     Result.push_back(Tok.deltaStart);
     Result.push_back(Tok.length);
     Result.push_back(Tok.tokenType);
     Result.push_back(Tok.tokenModifiers);
   }
   assert(Result.size() == SemanticTokenEncodingSize * Toks.size());
-  return Result;
+  return std::move(Result);
 }
 
 bool operator==(const SemanticToken &L, const SemanticToken &R) {
   return std::tie(L.deltaLine, L.deltaStart, L.length, L.tokenType,
                   L.tokenModifiers) == std::tie(R.deltaLine, R.deltaStart,
                                                 R.length, R.tokenType,
                                                 R.tokenModifiers);
 }

 }
 
 llvm::json::Value toJSON(const SemanticTokensOrEdits &TE) {
   llvm::json::Object Result{{"resultId", TE.resultId}};
   if (TE.edits)
     Result["edits"] = *TE.edits;
   if (TE.tokens)
     Result["data"] = encodeTokens(*TE.tokens);
-  return Result;
+  return std::move(Result);
 }
 
 bool fromJSON(const llvm::json::Value &Params, SemanticTokensParams &R) {
   llvm::json::ObjectMapper O(Params);
   return O && O.map("textDocument", R.textDocument);
 }
 
 bool fromJSON(const llvm::json::Value &Params, SemanticTokensEditsParams &R) {