Fix multiple cpptools processes running with a multiroot workspace. (#12461)

Author: sean-mcmanus

Extension/src/LanguageServer/client.ts

@@ -1204,7 +1204,7 @@ export class DefaultClient implements Client {
 
         try {
             let isFirstClient: boolean = false;
-            if (!languageClient || languageClientCrashedNeedsRestart) {
+            if (firstClientStarted === undefined || languageClientCrashedNeedsRestart) {
                 if (languageClientCrashedNeedsRestart) {
                     languageClientCrashedNeedsRestart = false;
                     // if we're recovering, the isStarted needs to be reset.